Angular 6 POST request sent out without Bearer token only with --prod?

I'm using Angular 6 with an HTTP Interceptor configured to apply bearer token to outgoing requests.

• In the dev build (ng serve), the token is applied and everything works fine. :-)

• In the production build (ng serve --prod) the request is sent out without bearer token. :-(

In the prod build, I have verified the header is being applied, by dumping the headers to the console after applying them.

I have no idea why they are excluded from the http request.

There are not differences in my environment files.

What else should I be looking at?

What can I do to fix this?

At first I thought this was an issue between my local environment and my staging environment, but then I tried running ng serve --prod locally and saw the same results.

All that to say, everything is identical except one being a production build and one being a dev build.

Here's the Interceptor code:

import { Injectable } from '@angular/core';
import { HttpRequest, HttpHandler, HttpEvent, HttpInterceptor } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable()
export class JwtInterceptor implements HttpInterceptor {
    intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

        // add authorization header with jwt token if available
        let currentUser = JSON.parse(localStorage.getItem('currentUser'));

        if (currentUser && currentUser.token) {
            request = request.clone({
                setHeaders: {
                    Authorization: `Bearer ${currentUser.token}`
                }
            });
            console.log('headers:', request.headers); // <---- I can see headers in console output
        }

        return next.handle(request);
    }
}

from Angular 6 POST request sent out without Bearer token only with --prod?