How to change the Vim Syntastic warning color in Airline using Solarized theme

Question

I'm using vim-syntastic and vim-airline using the solarized color theme.

When syntastic has a warning it displays in black on red, which is barely readable:

After reading the airline help I've tried something like this in my .vimrc:

call airline#parts#define_accent('syntastic', 'yellow')

which seems to have an effect, although 'yellow' is about the only color that is readable and noticeable:

But I have three questions:

1. I get an error when opening MacVim due to that call line:

   $ mvim index.html 
   Error detected while processing /Users/phil/.vimrc:
   line  304:
   E15: Invalid expression: 0:
   

   How do I prevent that?

2. I still get a bit of the error color at the right-edge of airline when there's no syntastic error:

   

   How do I prevent that?

3. Is this the right way to do this?

Answer 1

The answer to (1) is in two parts:

• I had a colon at the end of the line before the call line, which was causing the error.
• I am an idiot.