The global keydown handler calls event.key.toLowerCase() without checking
that event.key is defined. Some keydown events carry no key property
(browser autofill, IME composition, some mobile virtual keyboards), which
throws TypeError: Cannot read properties of undefined (reading
'toLowerCase') and breaks the handler for that keystroke.
Add a truthiness guard before calling toLowerCase(), matching the style
already used for the other event.key comparisons in the same handler.
No behavior change for real Cmd/Ctrl+K presses.
Yannick Tocquet