Refactor the app.route decorator

sanic/app.py

@@ -180,8 +180,14 @@ class Sanic:
             strict_slashes = self.strict_slashes
 
         def response(handler):
-            args = [key for key in signature(handler).parameters.keys()]
+            args = list(signature(handler).parameters.keys())
-            if args:
+
+            if not args:
+                raise ValueError(
+                    "Required parameter `request` missing "
+                    "in the {0}() route?".format(handler.__name__)
+                )
+
             if stream:
                 handler.is_stream = stream
 
@@ -195,11 +201,6 @@ class Sanic:
                 name=name,
             )
             return handler
-            else:
-                raise ValueError(
-                    "Required parameter `request` missing "
-                    "in the {0}() route?".format(handler.__name__)
-                )
 
         return response