Add filters and class based handler for errors

docs/dispatcher/class_based_handlers/error.md

@@ -0,0 +1,29 @@
+# ErrorHandler
+
+There is base class for error handlers.
+
+## Simple usage:
+```pyhton3
+from aiogram.handlers import ErrorHandler
+
+...
+
+@router.errors_handler()
+class MyHandler(ErrorHandler):
+    async def handle(self) -> Any:
+        log.exception(
+            "Cause unexpected exception %s: %s", 
+            self.event.__class__.__name__, 
+            self.event
+        )
+```
+
+## Extension
+
+This base handler is subclass of [BaseHandler](basics.md#basehandler)
+
+## Related pages
+
+- [BaseHandler](basics.md#basehandler)
+- [Router.errors_handler](../router.md#errors)
+- [Filters](../filters/exception.md)

docs/dispatcher/filters/exception.md

@@ -0,0 +1,27 @@
+# Exceptions
+This filters can be helpful for handling errors from the text messages.
+
+## ExceptionTypeFilter
+
+Allow to match exception by type
+
+### Specification
+| Argument | Type | Description |
+| --- | --- | --- |
+| `exception` |  `#!python3 Union[Type[Exception], Tuple[Type[Exception]]]` | Exception type(s) |
+
+
+## ExceptionMessageFilter
+
+Allow to match exception by message
+
+### Specification
+| Argument | Type | Description |
+| --- | --- | --- |
+| `match` |  `#!python3 Union[str, Pattern[str]]` | Regexp pattern |
+
+## Allowed handlers
+
+Allowed update types for this filters:
+
+- `error`

docs/dispatcher/router.md

@@ -116,6 +116,13 @@ async def poll_answer_handler(poll_answer: types.PollAnswer) -> Any: pass
 ```
 Is useful for handling [polls answers](../api/types/poll_answer.md)
 
+### Errors
+```python3
+@router.errors_handler()
+async def error_handler(exception: Exception) -> Any: pass
+```
+Is useful for handling errors from other handlers
+
 
 ## Nested routers