fix: resolve type checking error for DataFrame columns

Use conditional logic to create DataFrame with columns parameter
only when the event list is empty, avoiding type checking issues
with pyright while maintaining correct behavior.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: goloroden

eventsourcingdb/pandas.py

@@ -20,22 +20,6 @@ async def events_to_dataframe(events: AsyncGenerator[Event, None]) -> pd.DataFra
     Returns:
         A pandas DataFrame with all event fields as columns
     """
-    columns = [
-        "event_id",
-        "time",
-        "source",
-        "subject",
-        "type",
-        "data",
-        "spec_version",
-        "data_content_type",
-        "predecessor_hash",
-        "hash",
-        "trace_parent",
-        "trace_state",
-        "signature",
-    ]
-
     event_list = []
 
     async for event in events:
@@ -56,4 +40,23 @@ async def events_to_dataframe(events: AsyncGenerator[Event, None]) -> pd.DataFra
         }
         event_list.append(event_dict)
 
-    return pd.DataFrame(event_list, columns=columns)
+    if len(event_list) == 0:
+        return pd.DataFrame(
+            columns=[
+                "event_id",
+                "time",
+                "source",
+                "subject",
+                "type",
+                "data",
+                "spec_version",
+                "data_content_type",
+                "predecessor_hash",
+                "hash",
+                "trace_parent",
+                "trace_state",
+                "signature",
+            ]
+        )
+
+    return pd.DataFrame(event_list)