nodejs multer file upload, path contains double slashes

I am working on image upload via nodejs and multer module and this is the code im using:

app.post('/upload', upload.single('file'), function(req, res, next) {
    var tmp_path = req.file.path,
        target_path = __dirname + '/public/uploads/' + req.file.originalname,

        src = fs.createReadStream(tmp_path),
        dest = fs.createWriteStream(target_path);

    src.pipe(dest);
    fs.unlink(tmp_path); //deleting the tmp_path

    src.on('end', function() {
        res.json({
            success: true,
            file: '/uploads/' + req.file.originalname
        });
    });

    src.on('error', function(err) {
        console.log('err', err);
        res.json({
            success: false
        });
    });
});

The problem is that sometimes (it occures randomly) error callback is triggered, with this contents:

So it looks like additional slashes are added to the path which causes script not to find temp location and returns error, maybe someone encountered this problem and can help ;)

via Patrick Mevia