Fix error if data type is None

initdb/02_3_3_signalk_public_functions_py.sql

@@ -394,6 +394,9 @@ AS $geojson_py$
     import json
     parsed = json.loads(original)
     output = []
+    #plpy.notice(parsed)
+    # [None, None]
+    if None not in parsed:
         for idx, x in enumerate(parsed):
             #plpy.notice(idx, x)
             for feature in x: