If you type only spaces in the form and press Enter, it crashes.

It seems to have been self-resolved, but it seems to have been changed as follows:

Is there any coding that disables the enter key when the user presses the enter key without entering it or when the user presses the enter key with only the space key?

Debugging here

if(e.Key==Key.Enter&!String.IsNullOrEmpty(txtUrl.Text))

This line reads "Unhandled Exception System.ArgumentException: 'The value is not in the valid range.'

wbSample.Navigate(txtUrl.Text);

If you change the method used to make the decision from String.IsNullOrEmpty to String.IsNullOrWhiteSpace, it will work as you wish.

 if (e.Key==Key.Enter&!String.IsNullOrWhiteSpace(txtUrl.Text))

String.IsNullOrEmpty (String) method

Indicates whether the specified string is null or an empty string ("")

String.IsNullOrWhiteSpace (String) method

Indicates whether the specified string is null or empty or consists of only blank characters.

Only the problem points are pinpointed in the question, but you can work on the following article overview or tutorial to reproduce, investigate, and verify the problem.

Microsoft Edge WebView 2 Overview
Start using WebView 2 with the WinForms app

Paste the question code into the KeyDown event in the TextBox addressBar of the Tutorial above and adjust it to match the Tutorial content as follows:
Then you will be able to reproduce the problem, investigate it, and confirm the correction.

private void addressBar_KeyDown (object sender, System.Windows.Forms.KeyEventArgse)
{
    // When reproducing the problem: if(e.KeyCode==Keys.Enter&!String.IsNullOrEmpty(addressBar.Text))
    if(e.KeyCode==Keys.Enter&&!String.IsNullOrWhiteSpace(addressBar.Text))/Modified Edition
    {
        webView.CoreWebView2.Navigate(addressBar.Text);
    }
}