fix segfault on file open with zero tabs open
fix segfault on file open with zero tabs open

jmarshallnz/gummi,tonyolag/gummi-vim,jmarshallnz/gummi,tonyolag/gummi-vim,jmarshallnz/gummi,tonyolag/gummi-vim,jmarshallnz/gummi,tonyolag/gummi-vim