Code Hell: JavaScript Error Messages

When you’re tasked to make changes to a legacy 3000+ line JavaScript file, seeing this at the start doesn’t inspire confidence:

// ErrorMessage
this._EventLocationControl_JS_NoClientDataHolder_ErrorMessage = config.EventLocationControl_JS_NoClientDataHolder_ErrorMessage;
this._EventLocationControl_JS_InvalidMileMarker_ErrorMessage = config.EventLocationControl_JS_InvalidMileMarker_ErrorMessage;
this._EventLocationControl_JS_NoDefaultMap_ErrorMessage = config.EventLocationControl_JS_NoDefaultMap_ErrorMessage;
this._EventLocationControl_JS_NoMMService_ErrorMessage1 = config.EventLocationControl_JS_NoMMService_ErrorMessage1;
this._EventLocationControl_JS_NoMMService_ErrorMessage2 = config.EventLocationControl_JS_NoMMService_ErrorMessage2;
this._EventLocationControl_JS_NoMMServiceRoadway_ErrorMessage = config.EventLocationControl_JS_NoMMServiceRoadway_ErrorMessage;
this._EventLocationControl_JS_LoadDirection_ErrorMessage = config.EventLocationControl_JS_LoadDirection_ErrorMessage;
this._EventLocationControl_JS_NoMMCrossStreet_ErrorMessage = config.EventLocationControl_JS_NoMMCrossStreet_ErrorMessage;

this._EventLocationControl_JS_NoMMService_ErrorMessage3 = config.EventLocationControl_JS_NoMMService_ErrorMessage3;
this._EventLocationControl_JS_NoMMService_ErrorMessage4 = config.EventLocationControl_JS_NoMMService_ErrorMessage4;
this._EventLocationControl_JS_NoMMService_ErrorMessage5 = config.EventLocationControl_JS_NoMMService_ErrorMessage5;
this._EventLocationControl_JS_NoMMService_ErrorMessage6 = config.EventLocationControl_JS_NoMMService_ErrorMessage6;

this._EventLocationControl_JS_PreviewMapInvalidStartEnd_ErrorMessage = config.EventLocationControl_JS_PreviewMapInvalidStartEnd_ErrorMessage;
this._EventLocationControl_JS_PreviewMapInvalidLocation_ErrorMessage = config.EventLocationControl_JS_PreviewMapInvalidLocation_ErrorMessage;

this._EventLocationControl_JS_City_Text = config.EventLocationControl_JS_City_Text;
this._EventLocationControl_JS_County_Text = config.EventLocationControl_JS_County_Text;
this._EventLocationControl_JS_District_Text = config.EventLocationControl_JS_District_Text;