Repro Steps:

1) Within Studio, create a TextBlock.

2) Fill the 'Text' field of the TextBlock with any text you desire. ("Hello" for example).

3) Click off of the TextBlock's text field to set the text.

4) Click back on the TextBlock's text field, which will automatically select the entire previously-typed text string.

5) Press Backspace to delete the text within, but do not click outside of the field (keep the input field 'active', as visible by a blue outline around it, and a blinking text cursor within it)

6) Without moving the mouse, or clicking anywhere else, press Ctrl+W on the keyboard.

Observe how the application crashes.

Expected Result:
Pressing Ctrl+W after a field has been cleared should either:
A) Set the field as 'blank' before attempting to close the XAML Window (it should have a confirmation asking to save, similar to if you pressed the 'x' on the window to close it after making a change.
B) Function similarly to pressing 'Escape' - as in, reverting the field to its previous value, then attempting to close the XAML Window (and it should also present a Save confirmation modal if changes have been made since the last save)

I'm personally more tempted to go for B), but potentially to be discussed.