Code review fixes

core/data_store.py

@@ -106,6 +106,7 @@ class DataStore:
         and testing the callsign every time is expensive. So instead we build a separate in-memory lookup of compiled
         regex against DXCC entity code, as a list of tuples we can iterate through."""
 
+        self.dxcc_lookup_by_call_regex = []
         for entry in [DATA_STORE.dxcc_data[key] for key in DATA_STORE.dxcc_data]:
             self.dxcc_lookup_by_call_regex.append((re.compile(entry["prefixRegex"]), entry["entityCode"]))