Custom import fails when map file has a sourcesContent property set to an empty array

[SeinopSys]

I'm using node-sass and it automatically adds a sourcesContent key with an empty array as its value, which fools the app, and instead of asking for missing source files, it just says that they cannot be found.

To reproduce, add

sourcesContent: [],

to any valid map file and try to get to the 3rd import step. The import will fail.

[paulirish]

fixed in node-sass.
sass/node-sass#1045 (comment)