In your example when you remove the ink it still has the same behavior.

a better example would be the one from the docs

Material(
  color: Colors.teal[900],
  child: Center(
    child: Ink(
      color: Colors.yellow,
      width: 200.0,
      height: 100.0,
      child: InkWell(
        onTap: () { /* ... */ },
        child: Center(
          child: Text('YELLOW'),
        

Steps:

In sign in screen

1. Type email
2. Press 'Enter'
3. Note error message 'password should not be empty'
4. Start typing password

Expected behavior: error message should disappear.
Actual behavior: error message is still here.