Fix escaping in action error URL

packages/react-dom/src/__tests__/ReactDOMForm-test.js

@@ -922,4 +922,51 @@ describe('ReactDOMForm', () => {
     await act(() => resolveText('Wait'));
     assertLog(['Async action finished', 'No pending action']);
   });
+
+  // @gate enableFormActions
+  it('should error if submitting a form manually', async () => {
+    const ref = React.createRef();
+
+    let error = null;
+    let result = null;
+
+    function emulateForceSubmit(submitter) {
+      const form = submitter.form || submitter;
+      const action =
+        (submitter && submitter.getAttribute('formaction')) || form.action;
+      try {
+        if (!/\s*javascript:/i.test(action)) {
+          throw new Error('Navigate to: ' + action);
+        } else {
+          // eslint-disable-next-line no-new-func
+          result = Function(action.slice(11))();
+        }
+      } catch (x) {
+        error = x;
+      }
+    }
+
+    const root = ReactDOMClient.createRoot(container);
+    await act(async () => {
+      root.render(
+        <form
+          action={() => {}}
+          ref={ref}
+          onSubmit={e => {
+            e.preventDefault();
+            emulateForceSubmit(e.target);
+          }}>
+          <input type="text" name="foo" defaultValue="bar" />
+        </form>,
+      );
+    });
+
+    // This submits the form, which gets blocked and then resubmitted. It's a somewhat
+    // common idiom but we don't support this pattern unless it uses requestSubmit().
+    await submit(ref.current);
+    expect(result).toBe(null);
+    expect(error.message).toContain(
+      'A React form was unexpectedly submitted. If you called form.submit()',
+    );
+  });
 });