fixes the "Cursor position outside buffer"

[gachikuku]

Error on issue #157

[aarondill]

Note: this just reverts #156 and doesn't maintain the fix to that issue

[aarondill]

@gachikuku could you add these lines before line 28 and send a video showing the error again?

print("line: "..fn.line("."))
print("#lines: "..#lines)
print("rendered: "..state.rendered_completion)