FilterBox,BigNumber,WorldMap: Handle empty results (#9671)

This change avoids Pandas errors to pop up in chart when no data
is returned (confusing users). In this way a nicer
"No Results etc.." is returned.

superset/viz.py

@@ -1143,6 +1143,9 @@ class BigNumberViz(BaseViz):
         return d
 
     def get_data(self, df: pd.DataFrame) -> VizData:
+        if df.empty:
+            return None
+
         df = df.pivot_table(
             index=DTTM_ALIAS,
             columns=[],
@@ -1878,6 +1881,9 @@ class WorldMapViz(BaseViz):
         return qry
 
     def get_data(self, df: pd.DataFrame) -> VizData:
+        if df.empty:
+            return None
+
         from superset.examples import countries
 
         fd = self.form_data
@@ -1952,7 +1958,7 @@ class FilterBoxViz(BaseViz):
             col = flt.get("column")
             metric = flt.get("metric")
             df = self.dataframes.get(col)
-            if df is not None:
+            if df is not None and not df.empty:
                 if metric:
                     df = df.sort_values(
                         utils.get_metric_name(metric), ascending=flt.get("asc")
@@ -1967,6 +1973,8 @@ class FilterBoxViz(BaseViz):
                         {"id": row[0], "text": row[0]}
                         for row in df.itertuples(index=False)
                     ]
+        if not d:
+            return None
         return d