empty df fix

Author: ChristianBeilschmidt

geoengine/workflow.py

@@ -986,7 +986,8 @@ def data_usage(offset: int = 0, limit: int = 10) -> List[geoengine_openapi_clien
         # create dataframe from response
         usage_dicts = [data_usage.model_dump(by_alias=True) for data_usage in response]
         df = pd.DataFrame(usage_dicts)
-        df['timestamp'] = pd.to_datetime(df['timestamp'], utc=True)
+        if 'timestamp' in df.columns:
+            df['timestamp'] = pd.to_datetime(df['timestamp'], utc=True)
 
     return df
 
@@ -1008,6 +1009,7 @@ def data_usage_summary(granularity: geoengine_openapi_client.UsageSummaryGranula
         # create dataframe from response
         usage_dicts = [data_usage.model_dump(by_alias=True) for data_usage in response]
         df = pd.DataFrame(usage_dicts)
-        df['timestamp'] = pd.to_datetime(df['timestamp'], utc=True)
+        if 'timestamp' in df.columns:
+            df['timestamp'] = pd.to_datetime(df['timestamp'], utc=True)
 
     return df