[BUG][typescript-fetch] oneOf with arrays generate Typescript error

[GregoryMerlet]

Description

It seems that a change from #21464 broke the oneOf sample. Typescript now throw an error because of the last condition of the TestArrayResponseToJSONTyped method:
TS2339: Property every does not exist on type never

openapi-generator version

7.15.0

OpenAPI declaration file content or url

https://github.com/OpenAPITools/openapi-generator/blob/master/samples/client/petstore/typescript-fetch/builds/oneOf/models/TestArrayResponse.ts#L84

Generation Details

Steps to reproduce

Try compiling the oneOf sample with Typescript

[btpnlsl]

It looks like this is because the modelOneOf.mustache file is putting a return value; if the schema has an array of non-primitive objects:

    {{#oneOfArrays}}
    {{#-first}}
    if (Array.isArray(value)) {
        if (value.every(item => typeof item === 'object')) {
    {{/-first}}
            if (value.every(item => instanceOf{{{.}}}(item))) {
                return value.map(value => {{{.}}}ToJSON(value as {{{.}}}));
            }
    {{#-last}}
        }
        return value;
    }
    {{/-last}}
    {{/oneOfArrays}}

This return bypasses any further checks.