Log when no relevant samples are found for resampling

These additional logs will help in understanding
why certain microgrid components, such as meters,
fail to provide relevant samples for resampling.

Signed-off-by: Daniel Zullo <[email protected]>

Author: daniel-zullo-frequenz

src/frequenz/sdk/timeseries/_resampling.py

@@ -745,6 +745,8 @@ def resample(self, timestamp: datetime) -> Sample[Quantity]:
         # So if we need more performance beyond this point, we probably need to
         # resort to some C (or similar) implementation.
         relevant_samples = list(itertools.islice(self._buffer, min_index, max_index))
+        if not relevant_samples:
+            _logger.warning("No relevant samples found for component: %s", self._name)
         value = (
             conf.resampling_function(relevant_samples, conf, props)
             if relevant_samples