Errors handler

docs/dispatcher/middlewares/basics.md

@@ -29,6 +29,7 @@ Where is:
     - `#!python3 pre_checkout_query`
     - `#!python3 poll`
     - `#!python3 poll_answer`
+    - `#!python3 error`
 
 ## Connecting middleware with router
 
@@ -109,3 +110,6 @@ Returns `#!python3 Any`
 - `#!python3 on_pre_process_poll_answer` - will be triggered on **pre process** `#!python3 poll_answer` event
 - `#!python3 on_process_poll_answer` - will be triggered on **process** `#!python3 poll_answer` event
 - `#!python3 on_post_process_poll_answer` - will be triggered on **post process** `#!python3 poll_answer` event
+- `#!python3 on_pre_process_error` - will be triggered on **pre process** `#!python3 error` event
+- `#!python3 on_process_error` - will be triggered on **process** `#!python3 error` event
+- `#!python3 on_post_process_error` - will be triggered on **post process** `#!python3 error` event

docs/dispatcher/middlewares/index.md

@@ -46,6 +46,18 @@ Simple workflow:
 1. Call **post-process** update middleware in all routers tree
 1. Emit response into webhook (when it needed)
 
+!!! warning
+    When filters does not match any handler with this event the `#!python3 process` 
+    step will not be called.
+
+!!! warning
+    When exception will be caused in handlers pipeline will be stopped immediately 
+    and then start processing error via errors handler and it own middleware callbacks.
+
+!!! warning
+    Middlewares for updates will be called for all routers in tree but callbacks for events
+    will be called only for specific branch of routers.
+
 ### Pipeline in pictures:
 
 #### Simple pipeline