Fix swallowing of cancel error in Formula Engine & Voltage streamer

Signed-off-by: Mathias L. Baumann <[email protected]>

Author: Marenz

src/frequenz/sdk/timeseries/_voltage_streamer.py

@@ -190,6 +190,5 @@ async def _send_request(self) -> None:
                     "Phase-to-neutral 3-phase voltage streaming task cancelled: %s",
                     self._source_component,
                 )
-                break
-            else:
-                await sender.send(msg)
+                raise
+            await sender.send(msg)

src/frequenz/sdk/timeseries/formula_engine/_formula_engine.py

@@ -584,9 +584,8 @@ async def _run(self) -> None:
                 )
             except asyncio.CancelledError:
                 _logger.debug("FormulaEngine task cancelled: %s", self._name)
-                break
-            else:
-                await sender.send(msg)
+                raise
+            await sender.send(msg)
 
     def new_receiver(
         self, name: str | None = None, max_size: int = 50