[BUG] [Typescript] [angular] - 6.2.0 don't compile services in Typescript / TS2322: Type 'string | undefined' is not assignable to type 'string | string[]'

Created by: MassonGuillaume

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?
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Description

On typescript / angular, Typescript error on basePath length. Code generated fails with typescript error.

openapi-generator version

6.2.0 It is a regression from 6.0.1

Generation Details

With version 6.0.1 => ok

Error in 6.2.0 :

Suggest a fix

Fix proposition :

I will create a PR related to the bug.