Disable red squiggly underline

I have a single line editor control for showing just one line and most of the code using C# add on language, shows with a squiggly red line. I want the colour highlighting just don't want the red squiggly line. I would assume it displays this as it thinks theres a syntax error however it's only displaying one line at a time so this would obviously be the case if the editor doesn't know the full context in which the lines located