Update exception messages

Author: EmilyShepherd

src/Factory/Reflection/ReflectionMethodFactory.php

@@ -152,7 +152,11 @@ protected function addParamAnnotation($name, $value) : void
 
         if (!$this->parameters->containsKey($param))
         {
-            throw new \Exception();
+            throw new \Exception
+            (
+                  'Tried to set param annotation for non existant '
+                . 'parameter: ' . $param
+            );
         }
 
         $comparator = new TypeComparator();
@@ -162,7 +166,7 @@ protected function addParamAnnotation($name, $value) : void
 
         if (!$comparator->compatible($nativeType, $type))
         {
-            throw new \Exception();
+            throw new \Exception('Types are incompatible');
         }
 
         $param->setRawValue('type', $type);