Remove exceptions that are not actually raised from the docs

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

src/frequenz/channels/_anycast.py

@@ -425,7 +425,6 @@ def consume(self) -> _T:
 
         Raises:
             ReceiverStoppedError: If the receiver stopped producing messages.
-            ReceiverError: If there is some problem with the receiver.
         """
         if (  # pylint: disable=protected-access
             self._next is _Empty and self._channel._closed

src/frequenz/channels/_merge.py

@@ -179,7 +179,6 @@ def consume(self) -> ReceiverMessageT_co:
 
         Raises:
             ReceiverStoppedError: If the receiver stopped producing messages.
-            ReceiverError: If there is some problem with the receiver.
         """
         if not self._results and not self._pending:
             raise ReceiverStoppedError(self)

src/frequenz/channels/_receiver.py

@@ -450,7 +450,6 @@ def consume(self) -> ReceiverMessageT_co:
 
         Raises:
             ReceiverStoppedError: If the receiver stopped producing messages.
-            ReceiverError: If there is a problem with the receiver.
         """
         if self._recv_closed:
             raise ReceiverStoppedError(self)