chore: annotate important types (#36034)

Co-authored-by: Claude <noreply@anthropic.com>

superset/utils/core.py

@@ -1618,7 +1618,9 @@ def get_column_name_from_metric(metric: Metric) -> str | None:
     if is_adhoc_metric(metric):
         metric = cast(AdhocMetric, metric)
         if metric["expressionType"] == AdhocMetricExpressionType.SIMPLE:
-            return cast(dict[str, Any], metric["column"])["column_name"]
+            column = metric["column"]
+            if column:
+                return column["column_name"]
     return None