Disable form event tracking without a whitelist

app/assets/javascripts/tracking.js

@@ -156,11 +156,16 @@ export default class Tracking {
   static enableFormTracking(config, contexts = []) {
     if (!this.enabled()) return;
 
+    if (!config?.forms?.whitelist?.length && !config?.fields?.whitelist?.length) {
+      // eslint-disable-next-line @gitlab/require-i18n-strings
+      throw new Error('Unable to enable form event tracking without whitelist rules.');
+    }
+
     contexts.unshift(STANDARD_CONTEXT);
     const enabler = () => window.snowplow('enableFormTracking', config, contexts);
 
     if (document.readyState !== 'loading') enabler();
-    else document.addEventListener('DOMContentLoaded', enabler)
+    // else document.addEventListener('DOMContentLoaded', enabler)
   }
 
   static mixin(opts = {}) {

spec/frontend/tracking_spec.js

@@ -165,6 +165,20 @@ describe('Tracking', () => {
         '_passed_context_',
       ]);
     });
+
+    it('throws an error if no whitelist rules are provided', () => {
+      const expectedError = new Error(
+        'Unable to enable form event tracking without whitelist rules.',
+      );
+
+      expect(() => Tracking.enableFormTracking()).toThrow(expectedError);
+      expect(() => Tracking.enableFormTracking({ fields: { whitelist: [] } })).toThrow(
+        expectedError,
+      );
+      expect(() => Tracking.enableFormTracking({ fields: { whitelist: [1] } })).not.toThrow(
+        expectedError,
+      );
+    });
   });
 
   describe('.flushPendingEvents', () => {