[BUG][typescript-fetch] Set is not converted to Array when "typeMappings": { "Set": "Array"} is provided

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

I have get the error:
TypeError names?.find is not a function at runtime
page.bundle.js:6 A non-serializable value was detected in the state, in the path: model.modelInfo.names. Value: Set(2) {{…}, {…}}

openapi-generator version

OpenAPI declaration file content or url

Generation Details

Steps to reproduce

Run generator => run the app part that relates to using uniqueItems: true names property

Related issues/PRs

Suggest a fix

Start by reproducing the issue with the provided generator-cli configuration, the typescript-fetch generator, and an OpenAPI property using uniqueItems: true. Trace how the Set-to-Array type mapping is applied and compare the generated model with the runtime value; done means the property is represented as an Array and the reported runtime error no longer occurs.