Null pointer dereference

[xzyfer]

Originally reported by @MrTuxracer via HackerOne

@a(#{url(\#{})}

LibSass

[1]    73939 segmentation fault

Ruby Sass

Error: Invalid CSS after "@a(#{url(\#{": expected expression (e.g. 1px, bold), was "})}"
        on line 1 of test.scss

Spec sass/sass-spec#1105