(core) Fix delete user button for Google-only accounts

Summary:
An unhandled error was being thrown by CognitoClient when a user was unable
to be found during account deletion. Google-only accounts are no longer
associated with a user in Cognito, so the error was actually benign. A warning is
now logged instead.

Test Plan: Manual.

Reviewers: paulfitz, jarek

Reviewed By: paulfitz, jarek

Differential Revision: https://phab.getgrist.com/D4073

app/gen-server/lib/Doom.ts

@@ -117,8 +117,7 @@ export class Doom {
     await this._notifier.deleteUser(userId);
 
     // Remove user from cognito
-    const fullUser = this._dbManager.makeFullUser(user);
-    await this._loginSystem.deleteUser(fullUser);
+    await this._loginSystem.deleteUser(user);
 
     // Remove user from our db
     await this._dbManager.deleteUser({userId}, userId);

app/server/lib/GristServer.ts

@@ -1,7 +1,8 @@
 import { GristDeploymentType, GristLoadConfig } from 'app/common/gristUrls';
-import { FullUser, UserProfile } from 'app/common/UserAPI';
+import { UserProfile } from 'app/common/UserAPI';
 import { Document } from 'app/gen-server/entity/Document';
 import { Organization } from 'app/gen-server/entity/Organization';
+import { User } from 'app/gen-server/entity/User';
 import { Workspace } from 'app/gen-server/entity/Workspace';
 import { Activations } from 'app/gen-server/lib/Activations';
 import { HomeDBManager } from 'app/gen-server/lib/HomeDBManager';
@@ -57,7 +58,7 @@ export interface GristServer {
 
 export interface GristLoginSystem {
   getMiddleware(gristServer: GristServer): Promise<GristLoginMiddleware>;
-  deleteUser(user: FullUser): Promise<void>;
+  deleteUser(user: User): Promise<void>;
 }
 
 export interface GristLoginMiddleware {

app/server/lib/SamlConfig.ts

@@ -260,8 +260,9 @@ export async function getSamlLoginSystem(): Promise<GristLoginSystem|undefined>
         },
       };
     },
-    deleteUser() {
-      throw new Error('users cannot be deleted with SAML yet');
+    async deleteUser() {
+      // If we could delete the user account in the external
+      // authentication system, this is our chance - but we can't.
     },
   };
 }