diff --git a/acp/boardrules_info.php b/acp/boardrules_info.php
index 13af2932..f222f6ed 100644
--- a/acp/boardrules_info.php
+++ b/acp/boardrules_info.php
@@ -12,6 +12,11 @@
 
 class boardrules_info
 {
+	/**
+	 * Return ACP module configuration.
+	 *
+	 * @return array
+	 */
 	public function module()
 	{
 		return array(
diff --git a/acp/boardrules_module.php b/acp/boardrules_module.php
index d2399dc6..ed81755e 100644
--- a/acp/boardrules_module.php
+++ b/acp/boardrules_module.php
@@ -12,8 +12,13 @@
 
 class boardrules_module
 {
+	/** @var string */
 	public $page_title;
+
+	/** @var string */
 	public $tpl_name;
+
+	/** @var string */
 	public $u_action;
 
 	/**
@@ -21,6 +26,7 @@ class boardrules_module
 	 *
 	 * @param int $id
 	 * @param string $mode
+	 * @return void
 	 * @throws \Exception
 	 */
 	public function main($id, $mode)
diff --git a/controller/admin_controller.php b/controller/admin_controller.php
index 9ba50cb4..f62c447a 100644
--- a/controller/admin_controller.php
+++ b/controller/admin_controller.php
@@ -239,6 +239,7 @@ public function display_language_dashboard()
 	* @param int $parent_id Category to display rules from; default: 0
 	* @return void
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If stored rule data is invalid
 	*/
 	public function display_rules($language, $parent_id = 0)
 	{
@@ -295,7 +296,7 @@ public function display_rules($language, $parent_id = 0)
 			$this->template->assign_block_vars('breadcrumb', array(
 				'RULE_TITLE'		=> $entity->get_title(),
 
-				'S_CURRENT_LEVEL'	=> $entity->get_id() == $parent_id,
+				'S_CURRENT_LEVEL'	=> $entity->get_id() === (int) $parent_id,
 
 				'U_RULE'			=> "{$this->u_action}&language={$language}&parent_id=" . $entity->get_id(),
 			));
@@ -405,7 +406,7 @@ public function copy_ruleset($target_language, $return_to = '')
 			{
 				$copy_result = $this->ruleset_operator->copy($source_language, $target_language);
 			}
-			catch (\InvalidArgumentException | \RuntimeException $e)
+			catch (\Exception $e)
 			{
 				trigger_error($this->lang->lang($e->getMessage()) . adm_back_link($return_url), E_USER_WARNING);
 			}
@@ -508,6 +509,7 @@ protected function get_ruleset_return_url($language, $return_to)
 	* @param int $parent_id Category to display rules from; default: 0
 	* @return void
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If stored rule data is invalid
 	*/
 	public function add_rule($language, $parent_id = 0)
 	{
@@ -548,6 +550,7 @@ public function add_rule($language, $parent_id = 0)
 	* @param int $rule_id The rule identifier to edit
 	* @return void
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If the rule does not exist or stored rule data is invalid
 	*/
 	public function edit_rule($rule_id)
 	{
@@ -590,6 +593,7 @@ public function edit_rule($rule_id)
 	* @param array $data The form data to be processed
 	* @return void
 	* @access protected
+	* @throws \phpbb\boardrules\exception\base If stored rule data is invalid
 	*/
 	protected function add_edit_rule_data($entity, $data)
 	{
@@ -686,7 +690,7 @@ protected function add_edit_rule_data($entity, $data)
 				}
 
 				// Change rule parent
-				if (isset($data['rule_parent_id']) && ($data['rule_parent_id'] != $entity->get_parent_id()))
+				if (isset($data['rule_parent_id']) && ($entity->get_parent_id() !== (int) $data['rule_parent_id']))
 				{
 					try
 					{
@@ -765,6 +769,7 @@ protected function add_edit_rule_data($entity, $data)
 	* @param int $rule_id The rule identifier to delete
 	* @return void
 	* @access public
+	* @throws \phpbb\boardrules\exception\out_of_bounds If the rule does not exist
 	*/
 	public function delete_rule($rule_id)
 	{
@@ -813,6 +818,7 @@ public function delete_rule($rule_id)
 	* @param int $amount The number of places to move the rule
 	* @return void
 	* @access public
+	* @throws \phpbb\boardrules\exception\out_of_bounds If the rule does not exist after moving
 	*/
 	public function move_rule($rule_id, $direction, $amount = 1)
 	{
@@ -955,13 +961,14 @@ protected function has_copy_source(array $languages, $target_language)
 	}
 
 	/**
-	* Build pull down menu options of available rule parents
-	*
-	* @param \phpbb\boardrules\entity\rule_interface $entity The rule entity object
-	* @param int $parent_id Category to display rules from; default: 0
-	* @return void
-	* @access protected
-	*/
+	 * Build pull down menu options of available rule parents
+	 *
+	 * @param \phpbb\boardrules\entity\rule_interface $entity The rule entity object
+	 * @param int $parent_id Category to display rules from; default: 0
+	 * @return void
+	 * @access protected
+	 * @throws \phpbb\boardrules\exception\base If stored rule data is invalid
+	 */
 	protected function build_parent_select_menu($entity, $parent_id = 0)
 	{
 		// Prepare rule pull-down field
@@ -992,8 +999,8 @@ protected function build_parent_select_menu($entity, $parent_id = 0)
 				'RULE_ID'			=> $rule_menu_item->get_id(),
 				'RULE_TITLE'		=> $padding . $rule_menu_item->get_title(),
 
-				'S_DISABLED'		=> ($rule_menu_item->get_left_id() > $entity->get_left_id() && $rule_menu_item->get_right_id() < $entity->get_right_id()) || $rule_menu_item->get_id() == $entity->get_id(),
-				'S_RULE_PARENT'		=> $rule_menu_item->get_id() == $parent_id,
+				'S_DISABLED'		=> ($rule_menu_item->get_left_id() > $entity->get_left_id() && $rule_menu_item->get_right_id() < $entity->get_right_id()) || $rule_menu_item->get_id() === $entity->get_id(),
+				'S_RULE_PARENT'		=> $rule_menu_item->get_id() === (int) $parent_id,
 			));
 		}
 	}
diff --git a/controller/admin_interface.php b/controller/admin_interface.php
index 05004850..9071ec57 100644
--- a/controller/admin_interface.php
+++ b/controller/admin_interface.php
@@ -59,6 +59,7 @@ public function set_ruleset_published($language, $published, $return_to = '');
 	* @param int $parent_id Category to display rules from; default: 0
 	* @return void
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If stored rule data is invalid
 	*/
 	public function display_rules($language, $parent_id = 0);
 
@@ -77,6 +78,7 @@ public function save_ruleset_intro($language);
 	* @param int $parent_id Category to display rules from; default: 0
 	* @return void
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If stored rule data is invalid
 	*/
 	public function add_rule($language, $parent_id = 0);
 
@@ -86,6 +88,7 @@ public function add_rule($language, $parent_id = 0);
 	* @param int $rule_id The rule identifier to edit
 	* @return void
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If the rule does not exist or stored rule data is invalid
 	*/
 	public function edit_rule($rule_id);
 
@@ -95,6 +98,7 @@ public function edit_rule($rule_id);
 	* @param int $rule_id The rule identifier to delete
 	* @return void
 	* @access public
+	* @throws \phpbb\boardrules\exception\out_of_bounds If the rule does not exist
 	*/
 	public function delete_rule($rule_id);
 
@@ -106,6 +110,7 @@ public function delete_rule($rule_id);
 	* @param int $amount The number of places to move the rule
 	* @return void
 	* @access public
+	* @throws \phpbb\boardrules\exception\out_of_bounds If the rule does not exist after moving
 	*/
 	public function move_rule($rule_id, $direction, $amount = 1);
 
diff --git a/controller/main_controller.php b/controller/main_controller.php
index 2a30e8ed..15b548ab 100644
--- a/controller/main_controller.php
+++ b/controller/main_controller.php
@@ -74,6 +74,7 @@ public function __construct(\phpbb\config\config $config, \phpbb\controller\help
 	*
 	* @return \Symfony\Component\HttpFoundation\Response A Symfony Response object
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If stored rule data is invalid
 	*/
 	public function display()
 	{
@@ -176,7 +177,7 @@ public function display()
 		}
 
 		// Assign values to template vars for the rules page
-		$intro_text = (string) $this->ruleset_operator->get_intro_text($display_language);
+		$intro_text = $this->ruleset_operator->get_intro_text($display_language);
 
 		$this->template->assign_vars(array(
 			'S_BOARD_RULES'			=> true,
diff --git a/controller/main_interface.php b/controller/main_interface.php
index 6717cd49..44c242ec 100644
--- a/controller/main_interface.php
+++ b/controller/main_interface.php
@@ -22,6 +22,7 @@ interface main_interface
 	*
 	* @return \Symfony\Component\HttpFoundation\Response A Symfony Response object
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If stored rule data is invalid
 	*/
 	public function display();
 }
diff --git a/entity/rule.php b/entity/rule.php
index 5deeb93d..87b951ef 100644
--- a/entity/rule.php
+++ b/entity/rule.php
@@ -348,7 +348,7 @@ public function set_message($message)
 	/**
 	* Check if bbcode is enabled on the message
 	*
-	* @return int
+	* @return int OPTION_FLAG_BBCODE when enabled, otherwise 0
 	* @access public
 	*/
 	public function message_bbcode_enabled()
@@ -385,7 +385,7 @@ public function message_disable_bbcode()
 	/**
 	* Check if magic_url is enabled on the message
 	*
-	* @return int
+	* @return int OPTION_FLAG_LINKS when enabled, otherwise 0
 	* @access public
 	*/
 	public function message_magic_url_enabled()
@@ -422,7 +422,7 @@ public function message_disable_magic_url()
 	/**
 	* Check if smilies are enabled on the message
 	*
-	* @return int
+	* @return int OPTION_FLAG_SMILIES when enabled, otherwise 0
 	* @access public
 	*/
 	public function message_smilies_enabled()
diff --git a/entity/rule_interface.php b/entity/rule_interface.php
index a23dffbf..d687bf69 100644
--- a/entity/rule_interface.php
+++ b/entity/rule_interface.php
@@ -120,7 +120,7 @@ public function set_message($message);
 	/**
 	* Check if bbcode is enabled on the message
 	*
-	* @return bool
+	* @return int OPTION_FLAG_BBCODE when enabled, otherwise 0
 	* @access public
 	*/
 	public function message_bbcode_enabled();
@@ -144,7 +144,7 @@ public function message_disable_bbcode();
 	/**
 	* Check if magic_url is enabled on the message
 	*
-	* @return bool
+	* @return int OPTION_FLAG_LINKS when enabled, otherwise 0
 	* @access public
 	*/
 	public function message_magic_url_enabled();
@@ -168,7 +168,7 @@ public function message_disable_magic_url();
 	/**
 	* Check if smilies are enabled on the message
 	*
-	* @return bool
+	* @return int OPTION_FLAG_SMILIES when enabled, otherwise 0
 	* @access public
 	*/
 	public function message_smilies_enabled();
@@ -221,6 +221,7 @@ public function get_language();
 	 * @param string $language language iso
 	 * @return rule_interface $this object for chaining calls; load()->set()->save()
 	 * @access public
+	 * @throws \phpbb\boardrules\exception\unexpected_value If the language is not installed
 	 */
 	public function set_language($language);
 
diff --git a/migrations/helper.php b/migrations/helper.php
index b1c573e5..c4ebb8e6 100644
--- a/migrations/helper.php
+++ b/migrations/helper.php
@@ -47,6 +47,7 @@ public function __construct(\phpbb\db\driver\driver_interface $db, $table_prefix
 	 *
 	 * @param string $new_column Name of the column to be updated
 	 * @param string $old_column Name of the column with old data
+	 * @return void
 	 */
 	public function change_rule_language($new_column, $old_column)
 	{
diff --git a/migrations/v20x/m15_update_lang_schema.php b/migrations/v20x/m15_update_lang_schema.php
index 1708c776..530a59d7 100644
--- a/migrations/v20x/m15_update_lang_schema.php
+++ b/migrations/v20x/m15_update_lang_schema.php
@@ -78,6 +78,8 @@ public function update_data()
 
 	/**
 	 * Change rule_language values from lang_id to lang_iso
+	 *
+	 * @return void
 	 */
 	public function change_rule_language()
 	{
diff --git a/migrations/v20x/m16_update_lang_postgres.php b/migrations/v20x/m16_update_lang_postgres.php
index 20cb09f1..f673ba16 100644
--- a/migrations/v20x/m16_update_lang_postgres.php
+++ b/migrations/v20x/m16_update_lang_postgres.php
@@ -52,6 +52,7 @@ public function update_data()
 	 * To work around this, we re-create a new rule_language column with
 	 * the new data type and copy the new data to it via specific queries.
 	 *
+	 * @return void
 	 * @throws \RuntimeException
 	 */
 	public function alter_rule_language()
diff --git a/migrations/v30x/m18_ruleset_status.php b/migrations/v30x/m18_ruleset_status.php
index e0be345e..916e6d7f 100644
--- a/migrations/v30x/m18_ruleset_status.php
+++ b/migrations/v30x/m18_ruleset_status.php
@@ -12,11 +12,17 @@
 
 class m18_ruleset_status extends \phpbb\db\migration\migration
 {
+	/**
+	 * {@inheritdoc}
+	 */
 	public function effectively_installed()
 	{
 		return $this->db_tools->sql_table_exists($this->table_prefix . 'boardrules_rulesets');
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public static function depends_on()
 	{
 		return array(
@@ -25,6 +31,9 @@ public static function depends_on()
 		);
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function update_schema()
 	{
 		return array(
@@ -41,6 +50,9 @@ public function update_schema()
 		);
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function revert_schema()
 	{
 		return array(
diff --git a/migrations/v30x/m19_list_style_options.php b/migrations/v30x/m19_list_style_options.php
index 6aca7453..0547e159 100644
--- a/migrations/v30x/m19_list_style_options.php
+++ b/migrations/v30x/m19_list_style_options.php
@@ -12,11 +12,17 @@
 
 class m19_list_style_options extends \phpbb\db\migration\migration
 {
+	/**
+	 * {@inheritdoc}
+	 */
 	public function effectively_installed()
 	{
 		return $this->config['boardrules_list_style'] !== 'disc';
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public static function depends_on()
 	{
 		return array(
@@ -25,6 +31,9 @@ public static function depends_on()
 		);
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function update_data()
 	{
 		return array(
@@ -32,6 +41,9 @@ public function update_data()
 		);
 	}
 
+	/**
+	 * {@inheritdoc}
+	 */
 	public function revert_data()
 	{
 		return array(
diff --git a/operators/rule.php b/operators/rule.php
index 0ed1329f..c7c7fb25 100644
--- a/operators/rule.php
+++ b/operators/rule.php
@@ -50,8 +50,9 @@ public function __construct(ContainerInterface $container, \phpbb\boardrules\ope
 	*
 	* @param string $language Language selection iso
 	* @param int $parent_id Category to display rules from; default: 0
-	* @return array Array of rule data entities
+	* @return \phpbb\boardrules\entity\rule_interface[] Rule entities
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If stored rule data is invalid
 	*/
 	public function get_rules($language, $parent_id = 0)
 	{
@@ -81,6 +82,7 @@ public function get_rules($language, $parent_id = 0)
 	* @param int $parent_id Category to display rules from; default: 0
 	* @return \phpbb\boardrules\entity\rule_interface Added rule entity
 	* @access public
+	* @throws \RuntimeException If the nested-set lock cannot be acquired
 	* @throws \phpbb\boardrules\exception\out_of_bounds
 	*/
 	public function add_rule($entity, $language, $parent_id = 0)
@@ -122,6 +124,7 @@ public function add_rule($entity, $language, $parent_id = 0)
 	* @param int $rule_id The rule identifier to delete
 	* @return void
 	* @access public
+	* @throws \RuntimeException If the nested-set lock cannot be acquired
 	* @throws \phpbb\boardrules\exception\out_of_bounds
 	*/
 	public function delete_rule($rule_id)
@@ -147,6 +150,7 @@ public function delete_rule($rule_id)
 	* @param int $amount The number of places to move the rule
 	* @return void
 	* @access public
+	* @throws \RuntimeException If the nested-set lock cannot be acquired
 	* @throws \phpbb\boardrules\exception\out_of_bounds
 	*/
 	public function move($rule_id, $direction = 'up', $amount = 1)
@@ -172,6 +176,7 @@ public function move($rule_id, $direction = 'up', $amount = 1)
 	* @param int $new_parent_id The new rule parent identifier
 	* @return void
 	* @access public
+	* @throws \RuntimeException If the nested-set lock cannot be acquired
 	* @throws \phpbb\boardrules\exception\out_of_bounds
 	*/
 	public function change_parent($rule_id, $new_parent_id)
@@ -197,8 +202,9 @@ public function change_parent($rule_id, $new_parent_id)
 	*
 	* @param string $language Language selection iso
 	* @param int $parent_id Category to display rules from
-	* @return array Array of rule data for a rule's parent rules
+	* @return \phpbb\boardrules\entity\rule_interface[] Parent rule entities
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If stored rule data is invalid
 	*/
 	public function get_rule_parents($language, $parent_id)
 	{
diff --git a/operators/rule_interface.php b/operators/rule_interface.php
index 92616ec1..c8fd252e 100644
--- a/operators/rule_interface.php
+++ b/operators/rule_interface.php
@@ -22,8 +22,9 @@ interface rule_interface
 	*
 	* @param string $language Language selection iso
 	* @param int $parent_id Category to display rules from; default: 0
-	* @return array Array of rule data entities
+	* @return \phpbb\boardrules\entity\rule_interface[] Rule entities
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If stored rule data is invalid
 	*/
 	public function get_rules($language, $parent_id = 0);
 
@@ -33,8 +34,10 @@ public function get_rules($language, $parent_id = 0);
 	* @param \phpbb\boardrules\entity\rule_interface $entity Rule entity with new data to insert
 	* @param string $language Language selection iso
 	* @param int $parent_id Category to display rules from; default: 0
-	* @return rule_interface Added rule entity
+	* @return \phpbb\boardrules\entity\rule_interface Added rule entity
 	* @access public
+	* @throws \RuntimeException If the nested-set lock cannot be acquired
+	* @throws \phpbb\boardrules\exception\out_of_bounds If the entity was already inserted
 	*/
 	public function add_rule($entity, $language, $parent_id = 0);
 
@@ -44,6 +47,7 @@ public function add_rule($entity, $language, $parent_id = 0);
 	* @param int $rule_id The rule identifier to delete
 	* @return void
 	* @access public
+	* @throws \RuntimeException If the nested-set lock cannot be acquired
 	* @throws \phpbb\boardrules\exception\out_of_bounds
 	*/
 	public function delete_rule($rule_id);
@@ -56,6 +60,7 @@ public function delete_rule($rule_id);
 	* @param int $amount The number of places to move the rule
 	* @return void
 	* @access public
+	* @throws \RuntimeException If the nested-set lock cannot be acquired
 	* @throws \phpbb\boardrules\exception\out_of_bounds
 	*/
 	public function move($rule_id, $direction, $amount = 1);
@@ -67,6 +72,7 @@ public function move($rule_id, $direction, $amount = 1);
 	* @param int $new_parent_id The new rule parent identifier
 	* @return void
 	* @access public
+	* @throws \RuntimeException If the nested-set lock cannot be acquired
 	* @throws \phpbb\boardrules\exception\out_of_bounds
 	*/
 	public function change_parent($rule_id, $new_parent_id);
@@ -76,8 +82,9 @@ public function change_parent($rule_id, $new_parent_id);
 	*
 	* @param string $language Language selection iso
 	* @param int $parent_id Category to display rules from
-	* @return array Array of rule data for a rule's parent rules
+	* @return \phpbb\boardrules\entity\rule_interface[] Parent rule entities
 	* @access public
+	* @throws \phpbb\boardrules\exception\base If stored rule data is invalid
 	*/
 	public function get_rule_parents($language, $parent_id);
 }
diff --git a/operators/ruleset_interface.php b/operators/ruleset_interface.php
index dee30f03..cde55980 100644
--- a/operators/ruleset_interface.php
+++ b/operators/ruleset_interface.php
@@ -25,7 +25,9 @@ public function get_languages();
 	 * @param string $source_language
 	 * @param string $target_language
 	 * @return array Copy result containing rule and renamed-anchor counts
-	 * @throws \Exception
+	 * @throws \InvalidArgumentException If either language is invalid or source ruleset is empty
+	 * @throws \RuntimeException If nested-set lock cannot be acquired
+	 * @throws \Exception If ruleset persistence fails
 	 */
 	public function copy($source_language, $target_language);
 
@@ -55,6 +57,7 @@ public function get_intro_text($language);
 	 * @param string $language
 	 * @param string $intro_text
 	 * @return void
+	 * @throws \InvalidArgumentException If the language is not installed
 	 */
 	public function set_intro_text($language, $intro_text);
 
@@ -64,6 +67,7 @@ public function set_intro_text($language, $intro_text);
 	 * @param string $language
 	 * @param bool $published
 	 * @return void
+	 * @throws \InvalidArgumentException If the language is not installed or its ruleset is empty
 	 */
 	public function set_published($language, $published);
 }
diff --git a/tests/controller/admin_controller_test.php b/tests/controller/admin_controller_test.php
index e3f437ad..55a092ea 100644
--- a/tests/controller/admin_controller_test.php
+++ b/tests/controller/admin_controller_test.php
@@ -420,6 +420,28 @@ public function test_copy_ruleset_translates_operator_error(): void
 		$this->controller->copy_ruleset('fr');
 	}
 
+	public function test_copy_ruleset_handles_general_operator_exception(): void
+	{
+		$ruleset_operator = $this->getMockBuilder(\phpbb\boardrules\operators\ruleset::class)
+			->disableOriginalConstructor()
+			->setMethods(array('get_languages', 'copy'))
+			->getMock();
+		$ruleset_operator->method('get_languages')->willReturn(array(
+			array('lang_iso' => 'en', 'lang_local_name' => 'English', 'rule_count' => 3),
+			array('lang_iso' => 'fr', 'lang_local_name' => 'Français', 'rule_count' => 0),
+		));
+		$ruleset_operator->expects(self::once())
+			->method('copy')
+			->with('en', 'fr')
+			->willThrowException(new \Exception('ACP_BOARDRULES_COPY_FAILED'));
+		$this->replace_controller_service('ruleset_operator', $ruleset_operator);
+		$this->post['submit'] = true;
+		$this->variables['source_language'] = 'en';
+		$this->setExpectedTriggerError(E_USER_WARNING, 'ACP_BOARDRULES_COPY_FAILED');
+
+		$this->controller->copy_ruleset('fr');
+	}
+
 	public function test_copy_ruleset_rejects_invalid_form(): void
 	{
 		admin_test_state::$valid_form = false;
diff --git a/tests/event/listener_test.php b/tests/event/listener_test.php
index ab9f862c..5d80cb84 100644
--- a/tests/event/listener_test.php
+++ b/tests/event/listener_test.php
@@ -70,11 +70,13 @@ protected function setUp(): void
 				{
 					return array('_route' => 'phpbb_boardrules_main_controller');
 				}
-				else if ($path === '/runtime-error')
+
+				if ($path === '/runtime-error')
 				{
 					throw new \RuntimeException('Unable to match route.');
 				}
-				else if ($path === '/missing-route-name')
+
+				if ($path === '/missing-route-name')
 				{
 					return array();
 				}