message: fix categories/engines not being selected on game edit
  fixes:
diff: <app-form-control-errors />
  </app-form-group>
  + <!-- Gotta set keys for these since the data comes in async, vue
  + doesn't properly recheck the selected value after the categories
  + change. -->
  <app-form-group
  + :key="!!categories"
  name="category"
  :label="$gettext( `dash.games.form.category_label` )"
  >
  </app-form-group>
  <app-form-group
  + :key="!!engines"
  name="creation_tool"
  :label="$gettext( `dash.games.form.engine_label` )"
  >
  