yarn-plugin: validate version of yarn in yarn plugin

Signed-off-by: MT Lewis <mtlewis@users.noreply.github.com>

packages/yarn-plugin/package.json

@@ -34,6 +34,7 @@
     "@backstage/release-manifests": "workspace:^",
     "@yarnpkg/core": "^4.0.3",
     "@yarnpkg/fslib": "^3.0.2",
+    "chalk": "^4.0.0",
     "semver": "^7.6.0"
   },
   "devDependencies": {

packages/yarn-plugin/src/index.ts

@@ -21,10 +21,21 @@
  * @packageDocumentation
  */
 
-import { Plugin } from '@yarnpkg/core';
+import { Plugin, semverUtils, YarnVersion } from '@yarnpkg/core';
+import chalk from 'chalk';
 import { beforeWorkspacePacking } from './handlers/beforeWorkspacePacking';
 import { BackstageResolver } from './resolver/BackstageResolver';
 
+if (!semverUtils.satisfiesWithPrereleases(YarnVersion, '^4.1.1')) {
+  console.error();
+  console.error(
+    `${chalk.bold.red(
+      'Unsupported yarn version.',
+    )}: The Backstage yarn plugin only works with yarn ^4.1.1. Please upgrade yarn, or remove this plugin with "yarn plugin remove @yarnpkg/plugin-backstage".`,
+  );
+  console.error();
+}
+
 /**
  * @public
  */

yarn.lock

@@ -44721,6 +44721,7 @@ __metadata:
     "@yarnpkg/builder": ^4.0.0
     "@yarnpkg/core": ^4.0.3
     "@yarnpkg/fslib": ^3.0.2
+    chalk: ^4.0.0
     nodemon: ^3.0.1
     semver: ^7.6.0
   languageName: unknown