BUG: can't open a scratchpad in a vertical split

[beaumccartney]

Opening a scratchpad when windows are vertically split simply resizes one of the windows without opening a scratchpad

repro:

• open a file in nvim
• ctrl-w v to split the window
• call `:ScratchPad

NOTE: it doesn't fail in an empty buffer for me (i.e. nvim) but when a file is open it fails

EDIT: fix keymap to split window