Completely overhaul errors to be generated dynamically

telethon/_misc/binaryreader.py

@@ -7,7 +7,7 @@ from datetime import datetime, timezone, timedelta
 from io import BytesIO
 from struct import unpack
 
-from ..errors import TypeNotFoundError
+from ..errors._custom import TypeNotFoundError
 from .. import _tl
 from ..types import _core
 

telethon/_misc/entitycache.py

@@ -3,7 +3,7 @@ import itertools
 
 from .._misc import utils
 from .. import _tl
-from ..sessions.types import Entity
+from .._sessions.types import Entity
 
 # Which updates have the following fields?
 _has_field = {