Fix unexpected attribute error

Author: vladbarosan

apitools/base/protorpclite/protojson.py

@@ -333,7 +333,10 @@ def decode_field(self, field, value):
 
         elif (isinstance(field, messages.MessageField) and
               issubclass(field.type, messages.Message)):
-            return self.__decode_dictionary(field.type, value)
+            try:
+                return self.__decode_dictionary(field.type, value)
+            except AttributeError as err:
+                raise messages.DecodeError(err)
 
         elif (isinstance(field, messages.FloatField) and
               isinstance(value, (six.integer_types, six.string_types))):

apitools/base/protorpclite/protojson_test.py

@@ -374,14 +374,21 @@ def testDecodeInvalidDateTime(self):
                           MyMessage, '{"a_datetime": "invalid"}')
 
     def testDecodeInvalidMessage(self):
-        encoded = """{
-        "a_nested_datetime": {
-          "nested_dt_value": "invalid"
-          }
-        }
-        """
-        self.assertRaises(messages.DecodeError, protojson.decode_message,
-                          MyMessage, encoded)
+        for encoded in (
+                """{
+                  "a_nested_datetime": {
+                    "nested_dt_value": "invalid"
+                    }
+                  }
+                """,
+                """{
+                  "a_nested_datetime": [{
+                    "nested_dt_value": "2012-09-30T15:31:50.262"
+                    }]
+                  }
+                """):
+            self.assertRaises(messages.DecodeError, protojson.decode_message,
+                              MyMessage, encoded)
 
     def testEncodeDateTime(self):
         for datetime_string, datetime_vals in (