Show alert on opening about:home

src/background/usecases/operation.js

@@ -193,6 +193,10 @@ export default class OperationInteractor {
     let tab = await this.tabPresenter.getCurrent();
     let result = await browser.browserSettings.homepageOverride.get({});
     let us = urls.homepageUrls(result.value);
+    if (us.length === 1 && us[0] === 'about:home') {
+      // eslint-disable-next-line max-len
+      throw new Error('Cannot open Firefox Home (about:home) by WebExnteions, set your custom URLs');
+    }
     if (us.length === 1 && !newTab) {
       return this.tabPresenter.open(us[0], tab.id);
     }