Fixed bug that was caused by an even handler being called at an inapp…

…ropriate time

src/widgets/graphing_widget.py

@@ -553,6 +553,8 @@ def __on_data_name_chagned(self, new_table):
         def callback(work_result):
             self.remove_worker_by_jid(work_result.job_id)
             result = work_result.result
+            if result == None:
+                return
             if 'parameters' not in result:
                 self.set_graph_buttons_enabled(True)
                 return

src/worker/work_request.py

@@ -264,6 +264,8 @@ def table_meta_data(table_name: str):
         """
         *Initilizes meta data file.*
         """
+        if table_name == None or table_name == '':
+            return None
         table = LOCAL_TABLE_CACHE[table_name]['data']
         header = LOCAL_TABLE_CACHE[table_name]['header']
         parameters = list(table.keys())