来自svg-sprite的svg2png的UnhandledPromiseRejectionWarning错误

Question

gulp-svg2png无法正常工作，并出现以下错误UnhandledPromiseRejectionWarning我在该网站上进行了研究，在google上也发现了与我的情况完全相关的问题，但对于svg-sprite中的svg2png的UnhandledPromiseRejectionWarning没有正确答案

var gulp = require('gulp'),
    svgSprite = require('gulp-svg-sprite'),
    rename = require('gulp-rename'),
    del = require('del'),
    svg2png = require('gulp-svg2png');

// var config consist of mode we used, and it used the css mode
var config = {
    mode: {
        css: {
            sprite: 'sprite.svg',
            render: {
                css: {
                    template: './gulp/template/sprite.css'
                }
            }
        }
    }
}

gulp.task('beginClean', function() {
     return del(['./app/temp/sprite', './app/assets/images/sprites']);
});

gulp.task('createSprite', ['beginClean'], function() {
    return gulp.src('./app/assets/images/icons/**/*.svg')
        .pipe(svgSprite(config))
        .pipe(gulp.dest("./app/temp/sprite/"));
});

gulp.task('createPngCopy', ['createSprite'], function() {
    return gulp.src('./app/temp/sprite/css/*.svg')
    .pipe(svg2png())
    .pipe(gulp.dest('./app/temp/sprite/css'));
});

gulp.task('copySpriteGraphic', ['createPngCopy'], function() {
    return gulp.src('./app/temp/sprite/css/**/*.{svg,png}')
    .pipe(gulp.dest('./app/assets/images/sprites'));
});

gulp.task('copySpriteCSS', ['createSprite'], function() {
    return gulp.src('./app/temp/sprite/css/*.css')
    .pipe(rename('_sprite.css'))
    .pipe(gulp.dest('./app/assets/styles/modules'));
});

gulp.task('endClean', ['copySpriteGraphic', 'copySpriteCSS'], function() {
    return del('./app/temp/sprite'); 
});

gulp.task('icons', ['beginClean', 'createSprite', 'createPngCopy', 'copySpriteGraphic', 'copySpriteCSS', 'endClean']);