[Angular2 TypeScript] Query parameters: The left-hand side of an 'instanceof' expression must be of type 'any', an object type or a type parameter.

Description

Hi. I've started writing an API for a school project recently, and am using codegen to generate a client for my team-mate who is developping it using Angular2.

One of our first route uses number parameters. When compiling the whole thing, an error pops up:

error TS2358: The left-hand side of an 'instanceof' expression must be of type 'any', an object type or a type parameter.

After reading the code codegen generated, it seems that this part is causing it:

public getV1ClientPostsWithHttpInfo(start?: number, nb?: number, from?: number, to?: number, extraHttpRequestParams?: any): Observable<Response> {
    const path = this.basePath + `/v1/client/posts`;

    let queryParameters = new URLSearchParams();
    let headers = new Headers(this.defaultHeaders.toJSON()); // https://github.com/angular/angular/issues/6845
    if (start !== undefined) {
        if(start instanceof Date) {
            queryParameters.set('start', <any>start.d.toISOString());
        } else {
            queryParameters.set('start', <any>start);
        }
    }

I didn't include it in my paste, but the three remaining parameters get the same check.

The fails occurs at the if(start instanceof Date) part (and frankly I don't get why this check is performed, as there's no way a number type can be instance of Date).

Edit: After further research, it seems that only query params get this check (as described here).

Swagger-codegen version

Dunno if that's a regression as it's my first time using codegen. The version I'm using is 2.2.2.

Swagger declaration file content or url

Here's the route that's causing trouble:
https://gist.github.com/babolivier/2afd8207502c5ef498c0f7ca902d165a#file-swagger-json-L76-L126

This JSON file was generated by hapi-swagger

Command line used for generation

java -jar swagger-codegen-cli.jar generate -i http://127.0.0.1:3000/swagger.json -l typescript-angular2

Steps to reproduce

Related issues

Searched for one, came empty-handed.

Suggest a Fix

I don't know codegen's codebase enough to think of a fix. However, this instanceof is clearly unecessary and should be removed as it's causing the code not to compile.

Start with modules/swagger-codegen/src/main/resources/typescript-angular2/api.mustache, especially the query-parameter section linked in the issue, and reproduce the generated client with the supplied command and Swagger JSON. Confirm that generated Angular2 TypeScript clients with numeric query parameters compile without the reported TS2358 error.