add InvalidCredentialsError with language-agnostic code (#15472)

* add InvalidCredentialsError with language-agnostic code and update backend & web logout logic

* error.code in API error responses

Updated the error handler to serialize responseErr.code as the JSON error field, falling back to responseErr.name when no code is set.

* fix(lint): whitespace and missing def

* fix(lint): missed one

* add InvalidCredentialsError case for bad token

Add test verifying that auth middleware throws InvalidCredentialsError with code "invalid_credentials" and correct translated message when the API token is invalid.

* fix(test): user fields implicitly required

---------

Co-authored-by: Kalista Payne <sabrecat@gmail.com>

test/api/unit/middlewares/auth.test.js

@@ -60,5 +60,20 @@ describe('auth middleware', () => {
         return done();
       });
     });
+
+    it('errors with InvalidCredentialsError and code when token is wrong', done => {
+      const authWithHeaders = authWithHeadersFactory({ userFieldsToExclude: [] });
+
+      req.headers['x-api-user'] = user._id;
+      req.headers['x-api-key'] = 'totally-wrong-token';
+
+      authWithHeaders(req, res, err => {
+        expect(err).to.exist;
+        expect(err.name).to.equal('InvalidCredentialsError');
+        expect(err.code).to.equal('invalid_credentials');
+        expect(err.message).to.equal(res.t('invalidCredentials'));
+        return done();
+      });
+    });
   });
 });