[nan-661] fix invite flow (#1924)

## Describe your changes
Fix few logic errors with the invite flow.

## Issue ticket number and link
NAN-661

## Checklist before requesting a review (skip if just adding/editing
APIs & templates)
- [ ] I added tests, otherwise the reason is: 
- [ ] I added observability, otherwise the reason is:
- [ ] I added analytics, otherwise the reason is:

packages/server/lib/controllers/auth.controller.ts

@@ -354,7 +354,7 @@ class AuthController {
 
             const body: InviteAccountBody = req.body as InviteAccountBody;
 
-            if (!body || body.accountId !== undefined) {
+            if (!body || body.accountId === undefined) {
                 errorManager.errRes(res, 'missing_params');
                 return;
             }

packages/server/lib/controllers/user.controller.ts

@@ -1,7 +1,7 @@
 import { getUserAccountAndEnvironmentFromSession } from '../utils/utils.js';
 import type { Request, Response, NextFunction } from 'express';
 import EmailClient from '../clients/email.client.js';
-import { isCloud, isEnterprise, baseUrl } from '@nangohq/utils/dist/environment/detection.js';
+import { isCloud, isEnterprise, basePublicUrl } from '@nangohq/utils/dist/environment/detection.js';
 import { errorManager, userService } from '@nangohq/shared';
 
 export interface GetUser {
@@ -119,7 +119,7 @@ class UserController {
 
 <p>You are invited to join the ${account.name} account on Nango.</p>
 
-<p>Join this account by clicking <a href="${baseUrl}/signup/${invited?.token}">here</a> and completing your signup.</p>
+<p>Join this account by clicking <a href="${basePublicUrl}/signup/${invited?.token}">here</a> and completing your signup.</p>
 
 <p>Questions or issues? We are happy to help on the <a href="https://nango.dev/slack">Slack community</a>!</p>
 

packages/webapp/src/components/ui/button/Auth/Google.tsx

@@ -22,7 +22,7 @@ export default function GoogleButton({ text, setServerErrorMessage, invitedAccou
             }
         };
 
-        if (invitedAccountID && token) {
+        if (invitedAccountID !== null && invitedAccountID !== undefined && token) {
             postBody.body = JSON.stringify({
                 accountId: invitedAccountID
             });