More progress towards Alpha cleanup (#849)

* Get rid of unecessary parsing tests

* Finish up the migration of gadgets specific to Lurk data construction and deconstruction

src/coprocessor/circom.rs

@@ -118,9 +118,7 @@ Then run `lurk coprocessor --name {name} <{}_FOLDER>` to instantiate a new gadge
                     SynthesisError::Unsatisfiable
                 })?;
             let output = circom_scotia::synthesize(cs, self.config.r1cs.clone(), Some(witness))?;
-            let num_tag = g
-                .get_tag(&crate::tag::ExprTag::Num)
-                .expect("Num tag should have been allocated");
+            let num_tag = g.get_tag(&crate::tag::ExprTag::Num)?;
             let res = AllocatedPtr::from_parts(num_tag.clone(), output);
 
             Ok(res)