fix: Issue #4142 (#4144)

* Tweaks test in order to show the error

- Session is effectively created when it should not

* Do not create a session when users need verified accounts on signup

src/RestWrite.js

@@ -548,6 +548,11 @@ RestWrite.prototype.createSessionTokenIfNeeded = function() {
   if (this.query) {
     return;
   }
+  if (!this.storage['authProvider'] // signup call, with
+      && this.config.preventLoginWithUnverifiedEmail // no login without verification
+      && this.config.verifyUserEmails) { // verification is on
+    return; // do not create the session token in that case!
+  }
   return this.createSessionToken();
 }