Fix typing for ConnectionError.

aioredis/connection.py

@@ -23,6 +23,7 @@
     Type,
     TypeVar,
     Union,
+    cast,
 )
 from urllib.parse import ParseResult, parse_qs, unquote, urlparse
 
@@ -214,7 +215,7 @@ def on_connect(self, connection: "Connection"):
     async def can_read(self, timeout: float) -> bool:
         raise NotImplementedError()
 
-    async def read_response(self) -> Union[EncodableT, ResponseError, None]:
+    async def read_response(self) -> Union[EncodableT, ResponseError, None, List[EncodableT]]:
         raise NotImplementedError()
 
 
@@ -516,11 +517,12 @@ async def read_from_socket(
                 return False
             raise ConnectionError(f"Error while reading from socket: {ex.args}")
 
-    async def read_response(self) -> EncodableT:
+    async def read_response(self) -> Union[EncodableT, List[EncodableT]]:
         if not self._stream or not self._reader:
             self.on_disconnect()
             raise ConnectionError(SERVER_CLOSED_CONNECTION_ERROR) from None
 
+        response: Union[EncodableT, ConnectionError, List[Union[EncodableT, ConnectionError]]]
         # _next_response might be cached from a can_read() call
         if self._next_response is not False:
             response = self._next_response
@@ -538,12 +540,13 @@ async def read_response(self) -> EncodableT:
         if isinstance(response, ConnectionError):
             raise response
         elif (
-            isinstance(response, list)  # type: ignore[unreachable]
+            isinstance(response, list)
             and response
             and isinstance(response[0], ConnectionError)
         ):
             raise response[0]
-        return response
+        # cast as there won't be a ConnectionError here.
+        return cast(Union[EncodableT, List[EncodableT]], response)
 
 
 DefaultParser: Type[Union[PythonParser, HiredisParser]]