gui: show error message if Neovim exits with status != 0
gui: show error message if Neovim exits with status != 0

ngkaho1234/neovim-qt,equalsraf/neovim-qt,ngkaho1234/neovim-qt,ravloony/neovim-qt,equalsraf/neovim-qt,Pireax/neovim-qt,0x90sled/neovim-qt,ngkaho1234/neovim-qt,Pireax/neovim-qt,0x90sled/neovim-qt,ravloony/neovim-qt,equalsraf/neovim-qt,Pireax/neovim-qt,equalsraf/neovim-qt,ravloony/neovim-qt,0x90sled/neovim-qt