Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: penelopeysm

test/compiler.jl

@@ -611,7 +611,7 @@ module Issue537 end
         # Return-value when using `to_submodel`
         @model inner() = x ~ Normal()
         @model function outer()
-            _ignore ~ to_submodel(inner())
+            return _ignore ~ to_submodel(inner())
         end
         @test outer()() isa Real
 
@@ -712,7 +712,7 @@ module Issue537 end
             return (; x, y)
         end
         @model function demo_tracked_submodel()
-            vals ~ to_submodel(demo_tracked(), false)
+            return vals ~ to_submodel(demo_tracked(), false)
         end
         for model in [demo_tracked(), demo_tracked_submodel()]
             # Make sure it's runnable and `y` is present in the return-value.