SNOW-651560: Fix the metadata issue when extTypeName from the returned json result is empty (#1239)

Author: sfc-gh-jdu

src/snowflake/connector/cursor.py

@@ -132,7 +132,7 @@ def from_column(cls, col: dict[str, Any]):
             col["name"],
             FIELD_NAME_TO_ID[
                 col["extTypeName"].upper()
-                if "extTypeName" in col
+                if col.get("extTypeName")
                 else col["type"].upper()
             ],
             None,