scale plugin error attempt to index local 'text' (a nil value)

[pergus]

Changing the font size when there is only one line of text in a file generates an error:
data/core/common.lua:11 attempt to index local 'text' (a nil value)

Workaround:
Add a check to make sure that (n - view.size.y) isn't zero before line 51 in function set_scale to prevent a division by zero error.

Change:

   if n ~= math.huge and not view:is(CommandView) then
      scrolls[view] = view.scroll.y / (n - view.size.y)
    end

To:

    if n ~= math.huge and not view:is(CommandView) then
      if (n - view.size.y) ~= 0 then
        scrolls[view] = view.scroll.y / (n - view.size.y)
      end
    end