Fix the error sound effect when changing language

[torranx]

Fixes #832

The check for the sound effect can be found in src/ui/abstact-option-select-ui-handler.ts:

      if (option.handler()) {
        if (!option.keepOpen)
          this.clear();
        playSound = !option.overrideSound;
      } else
        ui.playError();

Since changeLocaleHandler() does not return anything (undefined), it will always resolve to the else statement.

Fix:

• Add boolean return value from changing locale handler