Make error handlers order of registration respected when handling errors

Author: avilaton

flask_restx/api.py

@@ -143,10 +143,10 @@ def __init__(
         self._default_error_handler = None
         self.tags = tags or []
 
-        self.error_handlers = {
+        self.error_handlers = OrderedDict({
             ParseError: mask_parse_error_handler,
             MaskError: mask_error_handler,
-        }
+        })
         self._schema = None
         self.models = {}
         self._refresolver = None
@@ -547,7 +547,7 @@ def __schema__(self):
 
     @property
     def _own_and_child_error_handlers(self):
-        rv = {}
+        rv = OrderedDict()
         rv.update(self.error_handlers)
         for ns in self.namespaces:
             for exception, handler in six.iteritems(ns.error_handlers):

flask_restx/namespace.py

@@ -4,7 +4,7 @@
 import inspect
 import warnings
 import logging
-from collections import namedtuple
+from collections import namedtuple, OrderedDict
 
 import six
 from flask import request
@@ -57,7 +57,7 @@ def __init__(
         self.urls = {}
         self.decorators = decorators if decorators else []
         self.resources = []  # List[ResourceRoute]
-        self.error_handlers = {}
+        self.error_handlers = OrderedDict()
         self.default_error_handler = None
         self.authorizations = authorizations
         self.ordered = ordered