Fix: saving empty query with auto limit crashes (#7430)

Co-authored-by: Eric Radman <[email protected]>

Author: yoshiokatsuneo

redash/query_runner/__init__.py

@@ -288,7 +288,10 @@ def supports_auto_limit(self):
         return True
 
     def query_is_select_no_limit(self, query):
-        parsed_query = sqlparse.parse(query)[0]
+        parsed_query_list = sqlparse.parse(query)
+        if len(parsed_query_list) == 0:
+            return False
+        parsed_query = parsed_query_list[0]
         last_keyword_idx = find_last_keyword_idx(parsed_query)
         # Either invalid query or query that is not select
         if last_keyword_idx == -1 or parsed_query.tokens[0].value.upper() != "SELECT":