chore: drop completion support (#915)

Author: mshima

lib/cli.js

@@ -12,7 +12,6 @@ import rootCheck from 'root-check';
 import meow from 'meow';
 import list from 'cli-list';
 import {bootstrap} from 'global-agent';
-import Tabtab from './completion/tabtab.cjs';
 import pkg from './utils/project-package.js';
 import Router from './router.js';
 import * as routes from './routes/index.js';
@@ -71,14 +70,7 @@ async function pre() {
   }
 
   if (cmd === 'completion') {
-    // eslint-disable-next-line new-cap
-    const tabtab = new Tabtab.Commands.default({
-      name: 'yo',
-      completer: 'yo-complete',
-      cache: false,
-    });
-
-    return tabtab.install();
+    throw new Error('Tabtab completion is no longer supported. See https://github.com/yeoman/yo/issues/886');
   }
 
   // Easteregg

lib/completion/completer.js

@@ -21,12 +21,6 @@ Run local generators:
 
   $ yo ./path/to/some/generator
 
-Completion:
-
-  To enable shell completion for the yo command, try running
-
-  $ yo completion
-
 Troubleshooting:
 
   For any issues, try running