[BUG] Javascript fails when anyOf is used

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
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Description

For the javascript API-Client for version 4.0.1 anyOf options give in correct results.

Using the following openapi.json.gz you get the following output:

Error: Cannot find module './AnyOffloatarray'
    at Function.Module._resolveFilename (module.js:547:15)
    at Function.Module._load (module.js:474:25)
    at Module.require (module.js:596:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/home/purcell/git/optimade-python-tools/javascript_client_generator/any_of_min_test/any_of/dist/model/TesterResponse.js:24:24)
    at Module._compile (module.js:652:30)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)

However by removing the anyOf portion of the file like openapi_no_anyof.json.gz it runs as expected.

This means that anyOf can not be used.

openapi-generator version

4.0.1

OpenAPI declaration file content or url

Run the listed generation, npm install, build, and Node reproduction using openapi.json; inspect the generated TesterResponse.js import that references the missing AnyOffloatarray module and trace the JavaScript generator's import handling. Done means a client generated from the anyOf specification builds and runs without the missing-module error.