nameCache option is causing trouble, error message is not helpful

[TheDcoder]

Hello,

I am getting a very ambiguous error in my gulp task since I have added the nameCache option to uglify pipe 😕

Here is the complete error:

GulpUglifyError: unable to minify JavaScript
Caused by: TypeError: Cannot read property 'cname' of undefined
File: E:\Projects\<redacted>\background.js

It does give the line number and my background.js script doesn't use any property called cname, so I am not sure what is the issue. Here is my pipe:

.pipe(uglify({
		mangle: {
			toplevel: true
		},
		compress: {properties: false},
		output: {quote_style: 3},
		nameCache: {}
	})).on('error', err => console.error(err.toString()))

It works perfectly without any warnings/errors if I remove nameCache: {}

Can anyone help me debug this? Thanks in advance! 😄

[LeonidasJP]

I've got a similar problem, where Uglify tries to read the unused property _walk of null... Though _walk is defined nowhere in my code...

My task:

// Concat Plugins, Minify
gulp.task('concatenate_plugins', function () {
    return gulp.src(['assets/js/plugins/**/*.js'])
        .pipe(concat('plugins.js'))
        .pipe(uglify({
            compress: {
                drop_console: true
            }
        }))
        .on('error', function(err) {
            console.error('Error in compress task', err.toString());
        })
        .pipe(rename({suffix: '.min'}))
        .pipe(gulp.dest(buildDir + '/assets'))
});

Output:

[] Using gulpfile C:\dev\<redacted>\gulpfile.js
[] Starting 'concatenate_plugins'...
Error in compress task GulpUglifyError: unable to minify JavaScript
Caused by: TypeError: Cannot read property '_walk' of null
File: C:\dev\<redacted>\assets\js\plugins.js

Process finished with exit code 0

The pipeline runs OK when not uglifying the code at all... Another task that runs uglify in the same way, runs successfully...

EDIT: After some digging, and removing scripts one by one that were being concatenated, I found the culprit: Tether v1.4.5 broke minification. v1.4.4 did not have any issues... This seems to be related to this Tether-issue: https://github.com/HubSpot/tether/issues/291