Import directives may not be used within control directives or mixins.

[eliezerpujols]

CSS file:

@include breakpoint() {
  @import "header";
}

Mixin file:

@mixin breakpoint() {
   @media (min-width: 480px) {@content;}
}

Sass fails with:

events.js:141
      throw er; // Unhandled 'error' event
      ^
 Error: src\main.scss
Error: Import directives may not be used within control directives or mixins.
        on line 59 of src/main.scss
>>    @import "header";
   -----------^

[eliezerpujols]

This issue was fixed in Sass Ruby: sass/libsass#1724

[xzyfer]

The issue you've linked to is the same error message but different circumstances. As the error states you cannot use @import inside of a mixin. This is part of the Sass language. Issues regards the Sass language need to opened with https://github.com/sass/sass