react-loadable-plugin. Handle undefined opts.caller (#25264)

`caller` - in babel is optional field - https://babeljs.io/docs/en/options#caller

And it may be not provided by developer in transformFile

## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.

## Documentation / Examples

- [ ] Make sure the linting passes

packages/next/build/babel/plugins/react-loadable-plugin.ts

@@ -151,7 +151,7 @@ export default function ({
                 t.binaryExpression(
                   '+',
                   t.stringLiteral(
-                    (state.file.opts.caller.pagesDir
+                    (state.file.opts.caller?.pagesDir
                       ? relativePath(
                           state.file.opts.caller.pagesDir,
                           state.file.opts.filename