Implemented error handler in dispatcher

(requested by @Oleg_Oleg_Oleg)

aiogram/dispatcher/__init__.py

@@ -3,7 +3,8 @@ import functools
 import logging
 import typing
 
-from .filters import CommandsFilter, ContentTypeFilter, RegexpFilter, USER_STATE, generate_default_filters
+from .filters import CommandsFilter, ContentTypeFilter, RegexpFilter, USER_STATE, generate_default_filters, \
+    ExceptionsFilter
 from .handler import Handler
 from .storage import BaseStorage, DisabledStorage, FSMContext
 from .webhook import BaseResponse
@@ -52,6 +53,8 @@ class Dispatcher:
 
         self.updates_handler.register(self.process_update)
 
+        self.errors_handlers = Handler(self, once=False)
+
         self._pooling = False
 
     def __del__(self):
@@ -93,6 +96,7 @@ class Dispatcher:
         :param update:
         :return:
         """
+        try:
             self.last_update_id = update.update_id
             has_context = context.check_configured()
             if update.message:
@@ -145,6 +149,11 @@ class Dispatcher:
                     state = self.storage.get_state(user=update.pre_checkout_query.from_user.id)
                     context.set_value(USER_STATE, await state)
                 return await self.pre_checkout_query_handlers.notify(update.pre_checkout_query)
+        except Exception as e:
+            err = await self.errors_handlers.notify(self, update, e)
+            if err:
+                return err
+            raise
 
     async def start_pooling(self, timeout=20, relax=0.1, limit=None):
         """
@@ -746,6 +755,35 @@ class Dispatcher:
 
         return decorator
 
+    def register_errors_handler(self, callback, *, func=None, exception=None):
+        """
+        Register errors handler
+
+        :param callback:
+        :param func:
+        :param exception: you can make handler for specific errors type
+        """
+        filters_set = []
+        if func is not None:
+            filters_set.append(func)
+        if exception is not None:
+            filters_set.append(ExceptionsFilter(exception))
+        self.errors_handlers.register(callback, filters_set)
+
+    def errors_handler(self, *, func=None, exception=None):
+        """
+        Decorator for registering errors handler
+
+        :param func:
+        :param exception: you can make handler for specific errors type
+        :return:
+        """
+        def decorator(callback):
+            self.register_errors_handler(callback, func=func, exception=exception)
+            return callback
+
+        return decorator
+
     def current_state(self, *,
                       chat: typing.Union[str, int, None] = None,
                       user: typing.Union[str, int, None] = None) -> FSMContext:

aiogram/dispatcher/filters.py

@@ -125,6 +125,19 @@ class StatesListFilter(StateFilter):
         return False
 
 
+class ExceptionsFilter(Filter):
+    def __init__(self, exception):
+        self.exception = exception
+
+    def check(self, dispatcher, update, exception):
+        try:
+            raise exception
+        except self.exception:
+            return True
+        except:
+            return False
+
+
 def generate_default_filters(dispatcher, *args, **kwargs):
     filters_set = []