cli: add esm loader for exterminal backend start

Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Co-authored-by: Johan Haals <johan.haals@gmail.com>
Co-authored-by: Camila Belo <camilaibs@gmail.com>
Co-authored-by: Philipp Hugenroth <philipph@spotify.com>
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/eighty-emus-float.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Add ESM loader for the experimental backend start command.

packages/cli/package.json

@@ -41,6 +41,7 @@
     "@backstage/release-manifests": "workspace:^",
     "@backstage/types": "workspace:^",
     "@esbuild-kit/cjs-loader": "^2.4.1",
+    "@esbuild-kit/esm-loader": "^2.5.5",
     "@manypkg/get-packages": "^1.1.3",
     "@octokit/graphql": "^5.0.0",
     "@octokit/graphql-schema": "^13.7.0",

packages/cli/src/lib/experimental/startBackendExperimental.ts

@@ -25,7 +25,12 @@ import debounce from 'lodash/debounce';
 import spawn from 'cross-spawn';
 import { paths } from '../paths';
 
-const loaderArgs = ['--require', require.resolve('@esbuild-kit/cjs-loader')];
+const loaderArgs = [
+  '--require',
+  require.resolve('@esbuild-kit/cjs-loader'),
+  '--loader',
+  require.resolve('@esbuild-kit/esm-loader'),
+];
 
 export async function startBackendExperimental(options: BackendServeOptions) {
   const envEnv = process.env as { NODE_ENV: string };

yarn.lock

@@ -3767,6 +3767,7 @@ __metadata:
     "@backstage/theme": "workspace:^"
     "@backstage/types": "workspace:^"
     "@esbuild-kit/cjs-loader": ^2.4.1
+    "@esbuild-kit/esm-loader": ^2.5.5
     "@manypkg/get-packages": ^1.1.3
     "@octokit/graphql": ^5.0.0
     "@octokit/graphql-schema": ^13.7.0
@@ -10758,6 +10759,16 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@esbuild-kit/esm-loader@npm:^2.5.5":
+  version: 2.5.5
+  resolution: "@esbuild-kit/esm-loader@npm:2.5.5"
+  dependencies:
+    "@esbuild-kit/core-utils": ^3.0.0
+    get-tsconfig: ^4.4.0
+  checksum: 9d4a03ffc937fbec75a8456c3d45d7cdb1a65768416791a5720081753502bc9f485ba27942a46f564b12483b140a8a46c12433a4496430d93e4513e430484ec7
+  languageName: node
+  linkType: hard
+
 "@esbuild/android-arm64@npm:0.16.17":
   version: 0.16.17
   resolution: "@esbuild/android-arm64@npm:0.16.17"