Fixed deleting session when requesting identity for invalid session (#19017)

ref https://ghost.slack.com/archives/C02G9E68C/p1700129928489809

- When the GET /api/session endpoint is called, the session is deleted
if it is invalid
- We don't have a body parser for this GET endoint, and the request
object was passed to the deleteSession handler. This caused a type error
(cannot read properties of undefined)
- We had dangling promise because deleteSession is async and wasn't
awaited, causing random errors in tests
- Added a test that would have caught this earlier

ghost/core/test/e2e-frontend/members.test.js

@@ -27,6 +27,12 @@ async function createMember(data) {
     });
 }
 
+async function cycleTransientId(data) {
+    return await members.api.members.cycleTransientId({
+        ...data
+    });
+}
+
 describe('Front-end members behavior', function () {
     let request;
 
@@ -100,6 +106,7 @@ describe('Front-end members behavior', function () {
 
         it('should return no content when removing member sessions', async function () {
             await request.del('/members/api/session')
+                .expect('set-cookie', /ghost-members-ssr=.*;.*?expires=Thu, 01 Jan 1970 00:00:00 GMT;.*?/)
                 .expect(204);
         });
 
@@ -550,6 +557,30 @@ describe('Front-end members behavior', function () {
                 member = await loginAsMember('member1@test.com');
             });
 
+            it('an invalid token causes a set-cookie logout when requesting the identity', async function () {
+                // Check logged in
+                await request.get('/members/api/member')
+                    .expect(200);
+
+                // Cycle the transient id manually
+                await cycleTransientId({id: member.id});
+
+                await member.refresh();
+                const transientId = member.get('transient_id');
+
+                await request.get('/members/api/session')
+                    .expect('set-cookie', /ghost-members-ssr=.*;.*?expires=Thu, 01 Jan 1970 00:00:00 GMT;.*?/)
+                    .expect(204);
+
+                // Check logged out
+                await request.get('/members/api/member')
+                    .expect(204);
+
+                // Check transient id has NOT changed
+                await member.refresh();
+                assert.equal(member.get('transient_id'), transientId);
+            });
+
             it('by default only destroys current session', async function () {
                 const transientId = member.get('transient_id');
 

ghost/members-ssr/lib/members-ssr.js

@@ -267,7 +267,7 @@ class MembersSSR {
      * @returns {Promise<void>}
      */
     async deleteSession(req, res) {
-        if (req.body.all) {
+        if (req.body && typeof req.body === 'object' && req.body.all) {
             // Update transient_id to invalidate all sessions
             const member = await this.getMemberDataFromSession(req, res);
             if (member) {
@@ -303,7 +303,7 @@ class MembersSSR {
         const transientId = this._getSessionCookies(req, res);
         const token = await this._getMemberIdentityToken(transientId);
         if (!token) {
-            this.deleteSession(req, res);
+            await this.deleteSession(req, res);
             throw new BadRequestError({
                 message: 'Invalid session, could not get identity token'
             });