gulp-sass, watch stops when invalid property name - node.js

Question

watch stops when error messages occur.
stream.js:94
throw er; // Unhandled stream error in pipe.
^
source string:51: error: invalid property name
How I can keep watch running and just to tell me where is the error located.
grunt could deal with errors and doesn't need to stop,
styleSheet.scss:41: error: invalid property name
otherwise, I need to keep typing "gulp" in the command-line when an error occurs.

Answer 1

This answer has been appended to reflect recent changes to Gulp. I've retained the original response, for relevance to the OPs question. If you are using Gulp 2.x, skip to the second section
Original response, Gulp 1.x
You may change this default behavior by passing errLogToConsole: true as an option to the sass() method.
Your task might look something like this, right now:
gulp.task('sass', function () {
gulp.src('./*.scss')
.pipe(sass())
.pipe(gulp.dest('./'));
});
Change the .pipe(sass()) line to include the errLogToConsole: true option:
.pipe(sass({errLogToConsole: true}))
This is what the task, with error logging, should look like:
gulp.task('sass', function () {
gulp.src('./*.scss')
.pipe(sass({errLogToConsole: true}))
.pipe(gulp.dest('./'));
});
Errors output will now be inline, like so:
[gulp] [gulp-sass] source string:1: error: invalid top-level expression
You can read more about gulp-sass options and configuration, on nmpjs.org
Gulp 2.x
In Gulp 2.x errLogToConsole may no longer be used. Fortunately, gulp-sass has a method for handling errors. Use on('error', sass.logError):
gulp.task('sass', function () {
gulp.src('./sass/**/*.scss')
.pipe(sass().on('error', sass.logError))
.pipe(gulp.dest('./css'));
});
If you need more fine-grained control, feel free to provide a callback function:
gulp.task('sass', function () {
gulp.src('./sass/**/*.scss')
.pipe(sass()
.on('error', function (err) {
sass.logError(err);
this.emit('end');
})
)
.pipe(gulp.dest('./css'));
});
This is a good thread to read if you need more information on process-control: https://github.com/gulpjs/gulp/issues/259#issuecomment-55098512

Answer 2

Actually above anwsers doesn't work for me (Im using gulp-sass 3.XX). What really worked:
gulp.task('sass', function () {
return gulp.src(config.scssPath + '/styles.scss')
.pipe(sourcemaps.init())
.pipe(sass({ outputStyle: 'compressed' })
.on('error', sass.logError)
)
.pipe(sourcemaps.write('./'))
.pipe(gulp.dest(config.cssPath))
});
In gulp-sass 3.x.x when I was using "sass.logError(err);" I constantly recive error that "this.emit('end'); is not a function". Now when I'm using:
.pipe(sass({ outputStyle: 'compressed' })
.on('error', sass.logError)
)
everything is working like a charm

Answer 3

In gulp "^2.0.0" the option errLogToConsole will no longer work. Instead gulp-sass has a built in error logging callback that uses gulp-util under the hood. Also, because gulp has some problems with killing the process on errors, if you are using with watch you will have to call this.emit('end')
https://github.com/gulpjs/gulp/issues/259#issuecomment-55098512
var sass = require('gulp-sass');
//dev
sass(config.sassDev)
.on('error', function(err) {
sass.logError(err);
this.emit('end'); //continue the process in dev
})
)
//prod
sass(config.sassProd).on('error', sass.logError)

Answer 4

A heads up for Gulp 3 users:
I liked #dtotheftp solution above, regarding gulp 2.x. Interestingly, it doesn't work unter Gulp3, at least not under #3.9.1:
.on('error', function(err){
sass.logError(err);
this.emit('end'); //continue the process in dev
})
gets me
TypeError: this.emit is not a function
at Function.logError (/depot/myproject/node_modules/gulp-sass/index.js:181:8)
Note, that the complaint is not coming from his this.emit() in the gulpfile but rather from the sass node-module, hence from the prior line.
This works for me:
.on('error', function(err){
gutil.log(err);
this.emit('end');
})
I do get all errors², and the watch never ends ;) (I am also using plumber() right after gulp.src(), which might help with that).
(Yes, the fix might be highly illogical, since sass.logError is said to be based on gutil...)
—
²also on undefined macros which went silent before on my setup for whatever reason.