What it sounds like
Username, edit text, required.
Before validation occurs, the linked error message should be set to display: none, or be empty.
What it looks like
Please enter a value.
<label for="sle-4">Username</label>
<input id="sle-4" aria-required="true" aria-describedby="sle-4" />
<p id="sle-4" class="visuallyhidden">Please enter a value.</p>