[BUG] [typescript-angular] cannot compile with noUncheckedIndexedAccess set to true

[jase88]

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• 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

If noUncheckedIndexedAccess is set to true in tsconfig.json, the embedded openapi generated code doesn't compile.

constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
        ...
        if (typeof this.configuration.basePath !== 'string') {
            if (Array.isArray(basePath) && basePath.length > 0) {
                basePath = basePath[0];
            }

basePath is type of string|string[] and basePath[0] could be undefined. This is in a way a compiler weakness rather than an error, because the length of the array is checked beforehand, whose data type is string[].

openapi-generator version

7.2.0

OpenAPI declaration file content or url

Generation Details

Steps to reproduce

Related issues/PRs

Suggest a fix

openapi-generator/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache

Line 75 in 7b0f963

basePath = basePath[0];

could be set to basePath = basePath[0]!;