fix(react-native): migration handles case where plugins is missing fr…

…om nx.json (#27387)

Otherwise, the migration will fail with an error.

<!-- Please make sure you have read the submission guidelines before
posting an PR -->
<!--
https://github.com/nrwl/nx/blob/master/CONTRIBUTING.md#-submitting-a-pr
-->

<!-- Please make sure that your commit message follows our format -->
<!-- Example: `fix(nx): must begin with lowercase` -->

<!-- If this is a particularly complex change or feature addition, you
can request a dedicated Nx release for this pull request branch. Mention
someone from the Nx team or the `@nrwl/nx-pipelines-reviewers` and they
will confirm if the PR warrants its own release for testing purposes,
and generate it for you if appropriate. -->

## Current Behavior
<!-- This is the behavior we have today -->

## Expected Behavior
<!-- This is the behavior we should expect with the changes in this PR
-->

## Related Issue(s)
<!-- Please link the issue being fixed so it gets closed when this is
merged. -->

Fixes #

packages/react-native/src/migrations/update-19-6-0/rename-upgrade-target-name.spec.ts

@@ -9,6 +9,10 @@ describe('rename-upgrade-target-name', () => {
     tree = createTreeWithEmptyWorkspace();
   });
 
+  it('should skip if no plugins', async () => {
+    expect(update(tree)).resolves.not.toThrow();
+  });
+
   it('should fix upgrade target name option', async () => {
     const nxJson = readNxJson(tree);
     nxJson.plugins = [

packages/react-native/src/migrations/update-19-6-0/rename-upgrade-target-name.ts

@@ -5,6 +5,7 @@ import { formatFiles, readNxJson, Tree, updateNxJson } from '@nx/devkit';
  */
 export default async function update(tree: Tree) {
   const nxJson = readNxJson(tree);
+  if (!nxJson.plugins) return;
   let updated = false;
   for (const plugin of nxJson.plugins) {
     if (typeof plugin === 'string') continue;