potentially solving the 'shipcall_id' error log

src/server/BreCal/database/sql_handler.py

@@ -207,6 +207,7 @@ class SQLHandler():
         returns: participant_id_list, where every element is an int
         """
         df = self.df_dict.get("shipcall_participant_map")
+        if 'shipcall_id' in list(df.columns):
             df = df.set_index('shipcall_id', inplace=False)
         
         # the 'if' call is needed to ensure, that no Exception is raised, when the shipcall_id is not present in the df