gulp-ruby-sass not working - gulp

Question

I did everything exactly as stated in docs:
https://github.com/sindresorhus/gulp-ruby-sass/blob/master/readme.md
This is my code in gulpfile.js:
// Sass configuration
const gulp = require('gulp');
const sass = require('gulp-ruby-sass');
const sourcemaps = require('gulp-sourcemaps');
gulp.task('sass', () =>
sass('kraater-web/src/app/css/admin/vars.scss', {sourcemap: true})
.on('error', sass.logError)
// for inline sourcemaps
.pipe(sourcemaps.write())
// for file sourcemaps
.pipe(sourcemaps.write('maps', {
includeContent: false,
sourceRoot: 'source'
}))
.pipe(gulp.dest('kraater-web/src/app/css/'))
);
gulp.task('default', ['sass'], function() {
})
When I run it, I just get this output, and no files are generated:
[15:47:25] Using gulpfile C:\wamp\www\site17\gulpfile.js
[15:47:25] Starting 'sass'...
[15:47:25] Could not find an option named "sourcemap".
[15:47:25] Usage: sass <input.scss> [output.css]
sass <input.scss>:<output.css> <input/>:<output/>
=== Input and Output ===================
--[no-]stdin Read the stylesheet from stdin.
--[no-]indented Use the indented syntax for input from stdin.
-I, --load-path=<PATH> A path to use when resolving imports.
May be passed multiple times.
-s, --style=<NAME> Output style.
[expanded (default), compressed]
--update Only compile out-of-date stylesheets.
=== Source Maps ========================
--[no-]source-map Whether to generate source maps.
(defaults to on)
--source-map-urls How to link from source maps to source files.
[relative (default), absolute]
--[no-]embed-sources Embed source file contents in source maps.
--[no-]embed-source-map Embed source map contents in CSS.
=== Other ==============================
-i, --interactive Run an interactive SassScript shell.
-c, --[no-]color Whether to emit terminal colors.
-q, --[no-]quiet Don't print warnings.
--[no-]trace Print full Dart stack traces for exceptions.
-h, --help Print this usage information.
--version Print the version of Dart Sass.
[15:47:25] Finished 'sass' after 416 ms
[15:47:25] Starting 'default'...
[15:47:25] Finished 'default' after 11 μs
Watching build tasks has finished.
Ideas how to get it to work?