(core) fix core build, and make smoke test more effective

Summary:
This makes the `core` test operate on a directory outside the
jenkins workspace, so that packages in the workspace don't
interfere with the test and obscure errors.

It also includes a small type fix for the `core` build.

Test Plan: updating a test

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3054

app/server/lib/Authorizer.ts

@@ -13,7 +13,7 @@ import {COOKIE_MAX_AGE, getAllowedOrgForSessionID, getCookieDomain,
         cookieName as sessionCookieName} from 'app/server/lib/gristSessions';
 import * as log from 'app/server/lib/log';
 import {IPermitStore, Permit} from 'app/server/lib/Permit';
-import {allowHost} from 'app/server/lib/requestUtils';
+import {allowHost, optStringParam} from 'app/server/lib/requestUtils';
 import * as cookie from 'cookie';
 import {NextFunction, Request, RequestHandler, Response} from 'express';
 import * as onHeaders from 'on-headers';
@@ -192,7 +192,7 @@ export async function addRequestUser(dbManager: HomeDBManager, permitStore: IPer
 
     // See if we have a profile linked with the active organization already.
     // TODO: implement userSelector for rest API, to allow "sticky" user selection on pages.
-    let sessionUser: SessionUserObj|null = getSessionUser(session, mreq.org, mreq.query.user || '');
+    let sessionUser: SessionUserObj|null = getSessionUser(session, mreq.org, optStringParam(mreq.query.user) || '');
 
     if (!sessionUser) {
       // No profile linked yet, so let's elect one.