core-api: workaround for backend:dev port conflict issue

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/perfect-scissors-swim.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Fixed an issue where the `backend:dev` command would get stuck executing the backend process multiple times, causing port conflict issues.

packages/cli/src/commands/backend/dev.ts

@@ -14,10 +14,17 @@
  * limitations under the License.
  */
 
+import fs from 'fs-extra';
 import { Command } from 'commander';
+import { paths } from '../../lib/paths';
 import { serveBackend } from '../../lib/bundler/backend';
 
 export default async (cmd: Command) => {
+  // Cleaning dist/ before we start the dev process helps work around an issue
+  // where we end up with the entrypoint executing multiple times, causing
+  // a port bind conflict among other things.
+  await fs.remove(paths.resolveTarget('dist'));
+
   const waitForExit = await serveBackend({
     entry: 'src/index',
     checksEnabled: cmd.check,