Workers can't recover from no `distPath`.

[nathanhammond]

Workers are started just once:

fastboot-app-server/src/fastboot-app-server.js

Line 53 in a5d194e

this.worker.start();

this.middleware is only set here:

fastboot-app-server/src/worker.js

Lines 45 to 49 in a5d194e

	if (!this.distPath) {
	this.middleware = this.noAppMiddleware();
	} else {
	this.middleware = this.buildMiddleware();
	}

And then you're stuck with that middleware forever:

fastboot-app-server/src/worker.js

Line 87 in a5d194e

return this.httpServer.serve(this.middleware)

For bonus points, fastbootMiddleware here:

fastboot-app-server/src/express-http-server.js

Line 26 in a5d194e

serve(fastbootMiddleware) {

...is therefore possibly not a FastBoot middleware which is a super troll since we expose httpServer as a downstream API.