Avoid errors when variables or protection rules are unset

Signed-off-by: Kyle Harding <kyle@balena.io>

lib/plugins/environments.js

@@ -231,7 +231,7 @@ module.exports = class Environments extends Diffable {
       wait_timer: attrs.wait_timer,
       prevent_self_review: attrs.prevent_self_review,
       reviewers: attrs.reviewers,
-      deployment_branch_policy: attrs.deployment_branch_policy === null
+      deployment_branch_policy: attrs.deployment_branch_policy == null
         ? null
         : {
             protected_branches: attrs.deployment_branch_policy.protected_branches,
@@ -250,23 +250,27 @@ module.exports = class Environments extends Diffable {
       }
     }
 
-    for (const variable of attrs.variables) {
-      await this.github.request('POST /repos/:org/:repo/environments/:environment_name/variables', {
-        org: this.repo.owner,
-        repo: this.repo.repo,
-        environment_name: attrs.name,
-        name: variable.name,
-        value: variable.value
-      })
+    if (attrs.variables) {
+      for (const variable of attrs.variables) {
+        await this.github.request('POST /repos/:org/:repo/environments/:environment_name/variables', {
+          org: this.repo.owner,
+          repo: this.repo.repo,
+          environment_name: attrs.name,
+          name: variable.name,
+          value: variable.value
+        })
+      }
     }
 
-    for (const rule of attrs.deployment_protection_rules) {
-      await this.github.request('POST /repos/:org/:repo/environments/:environment_name/deployment_protection_rules', {
-        org: this.repo.owner,
-        repo: this.repo.repo,
-        environment_name: attrs.name,
-        integration_id: rule.app_id
-      })
+    if (attrs.deployment_protection_rules) {
+      for (const rule of attrs.deployment_protection_rules) {
+        await this.github.request('POST /repos/:org/:repo/environments/:environment_name/deployment_protection_rules', {
+          org: this.repo.owner,
+          repo: this.repo.repo,
+          environment_name: attrs.name,
+          integration_id: rule.app_id
+        })
+      }
     }
   }