Is there a way to change the size of the font in the error console?

[Kevin]

And the answer is, yes you can:
   

You just need this in the gtkrc for the theme:

Code:

style "errorview"
{
  base[NORMAL] = "#202020"
  text[NORMAL] = "#ff8000"          # make the warning messages stand out by making them orange
  font_name = "sans, 20"
}

widget "*GimpErrorConsole*GtkScrolledWindow*"   style:highest "errorview" # specifically for the scrolled window on the error console

The widget specification is specifically targeting just the error console, so it's shouldn't have any side effects elsewhere.