(core) Fix for tests failures

Summary:
- DocApi test for Allowed Origin was using a home server endpoint
- Fixing waitForServer, as gristApp can be unavailable for a moment when browser is refreshed
- Fixing MergedOrgs tests typing issue

Test Plan: Updated

Reviewers: cyprien, paulfitz

Reviewed By: cyprien, paulfitz

Subscribers: paulfitz

Differential Revision: https://phab.getgrist.com/D3648

test/nbrowser/gristUtils.ts

@@ -831,7 +831,7 @@ export async function waitAppFocus(yesNo: boolean = true): Promise<void> {
  */
 export async function waitForServer(optTimeout: number = 2000) {
   await driver.wait(() => driver.executeScript(
-    "return (!window.gristApp.comm || !window.gristApp.comm.hasActiveRequests())"
+    "return window.gristApp && (!window.gristApp.comm || !window.gristApp.comm.hasActiveRequests())"
     + " && window.gristApp.testNumPendingApiRequests() === 0",
     optTimeout,
     "Timed out waiting for server requests to complete"