Freeze DEFAULT_OPTIONS to prevent accidental edits

src/common/services/OptionsService.ts

@@ -15,7 +15,7 @@ import { clone } from 'common/Clone';
 export const DEFAULT_BELL_SOUND = 'data:audio/wav;base64,UklGRigBAABXQVZFZm10IBAAAAABAAEARKwAAIhYAQACABAAZGF0YQQBAADpAFgCwAMlBZoG/wdmCcoKRAypDQ8PbRDBEQQTOxRtFYcWlBePGIUZXhoiG88bcBz7HHIdzh0WHlMeZx51HmkeUx4WHs8dah0AHXwc3hs9G4saxRnyGBIYGBcQFv8U4RPAEoYRQBACD70NWwwHC6gJOwjWBloF7gOBAhABkf8b/qv8R/ve+Xf4Ife79W/0JfPZ8Z/wde9N7ijtE+wU6xvqM+lb6H7nw+YX5mrlxuQz5Mzje+Ma49fioeKD4nXiYeJy4pHitOL04j/jn+MN5IPkFOWs5U3mDefM55/ogOl36m7rdOyE7abuyu8D8Unyj/Pg9D/2qfcb+Yn6/vuK/Qj/lAAlAg==';
 
 // TODO: Freeze?
-export const DEFAULT_OPTIONS: ITerminalOptions = {
+export const DEFAULT_OPTIONS: ITerminalOptions = Object.freeze({
   cols: 80,
   rows: 24,
   cursorBlink: false,
@@ -47,7 +47,7 @@ export const DEFAULT_OPTIONS: ITerminalOptions = {
   debug: false,
   cancelEvents: false,
   useFlowControl: false
-};
+});
 
 /**
  * The set of options that only have an effect when set in the Terminal constructor.