[BUG] [typescript-fetch] cannot compile with noUncheckedIndexedAccess

Created by: javier-garcia-meteologica

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Description

When noUncheckedIndexedAccess is enabled in tsconfig.json, openapi generated code doesn't compile.

The problem is that params[key] could be undefined but that type is not listed in the value argument of querystringSingleKey.

https://github.com/OpenAPITools/openapi-generator/blob/6948f1551448194c9d0f6881eb207c99d3b85bf0/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache#L258-L263

[tsl] ERROR in .../src/api/runtime.ts(263,47)                                                        
      TS2345: Argument of type 'string | number | boolean | HTTPQuery | (string | number | boolean | null)[] | Set<string | number | boolean | null> | null | undefined' is not assignable to parameter of type 'string | number | boolean | HTTPQuery | (string | number | boolean | null)[] | Set<string | number | boolean | null> | null'.                                                                                                                                                                                                 
  Type 'undefined' is not assignable to type 'string | number | boolean | HTTPQuery | (string | number | boolean | null)[] | Set<string | number | boolean | null> | null'.

openapi-generator version

6.0.0

OpenAPI declaration file content or url

{
"$schema": "node_modules/@openapitools/openapi-generator-cli/config.schema.json",
"spaces": 2,
"generator-cli": {
  "version": "6.0.0",
  "generators": {
    "typescript": {
      "generatorName": "typescript-fetch",
      "output": "#{cwd}/src/api",
      "inputSpec": "../backend/src/definitions/auth/v1/openapi.json",
      "additionalProperties": {
        "typescriptThreePlus": true,
        "withoutRuntimeChecks": true
      }
    }
  }
}
}

Generation Details

npm exec --package=@openapitools/openapi-generator-cli -- openapi-generator-cli generate

Steps to reproduce

Related issues/PRs

Suggest a fix

#12543