Hello,
I have noticed certain fail() calls include newline. This does not seem necessary since fail() is defined as 
    printf(
        "seL4 called fail at %s:%u in function %s, saying \"%s\"\n",
        file,
        line,
        function,
        s
    );
Which causes affected error messages to contain a single " character on a new line.
Patch attached.
Regards,
Eduard Nicodei