Why did my gulpfile stop working?

Question

gulp.js

Hello everyone!
Somewhere in the middle of summer (2018) I compiled my gallp file:

'use strict';

var gulp = require('gulp'),
    mainBowerFiles = require('main-bower-files'),
    watch = require('gulp-watch'),
    prefixer = require('gulp-autoprefixer'),
    uglify = require('gulp-uglify'),
    sourcemaps = require('gulp-sourcemaps'),
    sass = require('gulp-sass'),
    cleanCSS = require('gulp-clean-css'),
    imagemin = require('gulp-imagemin'),
    pngquant = require('imagemin-pngquant'),
    rimraf = require('rimraf'),
    browserSync = require("browser-sync"),
    reload = browserSync.reload;

var path = {
    vendor: {
        js: 'app/js/',
        css: 'app/css/'
    },
    dist: { 
        html: 'dist/',
        js: 'dist/js/',
        scss: 'dist/css/',
        css: 'dist/css/',
        img: 'dist/img/',
        fonts: 'dist/fonts/'
    },
    app: { 
        html: 'app/*.html',
        js: 'app/js/*.js', 
        scss: 'app/css/*.scss',
        css: 'app/css/*.css',
        img: 'app/img/**/*.*', 
        fonts: 'app/fonts/**/*.*'
    },
    watch: {
        html: 'app/**/*.html',
        js: 'app/js/**/*.js',
        scss: 'app/css/**/*.scss',
        css: 'app/css/**/*.css',
        img: 'app/img/**/*.*',
        fonts: 'app/fonts/**/*.*'
    },
    clean: './dist'
};

var config = {
    server: {
        baseDir: "./dist"
    },
};

gulp.task('vendorJs:build', function() {
    gulp.src(mainBowerFiles('**/*.js')) 
        .pipe(gulp.dest(path.vendor.js))
});

gulp.task('vendorCss:build', function() {
    gulp.src(mainBowerFiles('**/*.css')) 
        .pipe(gulp.dest(path.vendor.css)) 
});

gulp.task('html:build', function() {
    gulp.src(path.app.html)
        .pipe(gulp.dest(path.dist.html)) 
        .pipe(reload({ stream: true })); 
});

gulp.task('js:build', function() {
    gulp.src(path.app.js)
        .pipe(sourcemaps.init())
        .pipe(uglify()) 
        .pipe(sourcemaps.write()) 
        .pipe(gulp.dest(path.dist.js))
        .pipe(reload({ stream: true })); 
});

gulp.task('scss:build', function() {
    gulp.src(path.app.scss) 
        .pipe(sourcemaps.init()) 
        .pipe(sass())
        .pipe(prefixer()) 
        .pipe(cleanCSS()) 
        .pipe(sourcemaps.write())
        .pipe(gulp.dest(path.dist.scss))
        .pipe(reload({ stream: true }));
});

gulp.task('css:build', function() {
    gulp.src(path.app.css) 
        .pipe(sourcemaps.init())
        .pipe(gulp.dest(path.dist.css)) 
        .pipe(reload({ stream: true }));
});

gulp.task('image:build', function() {
    gulp.src(path.app.img) 
        .pipe(imagemin({ 
            progressive: true,
            svgoPlugins: [{ removeViewBox: false }],
            use: [pngquant()],
            interlaced: true
        }))
        .pipe(gulp.dest(path.dist.img)) 
        .pipe(reload({ stream: true }));
});

gulp.task('fonts:build', function() {
    gulp.src(path.app.fonts)
        .pipe(gulp.dest(path.dist.fonts))
});

gulp.task('build', [
    'vendorCss:build',
    'vendorJs:build',
    'html:build',
    'js:build',
    'scss:build',
    'css:build',
    'fonts:build',
    'image:build'
]);

gulp.task('watch', function() {
    watch([path.watch.html], function(event, cb) {
        gulp.start('html:build');
    });
    watch([path.watch.scss], function(event, cb) {
        gulp.start('scss:build');
    });
    watch([path.watch.css], function(event, cb) {
        gulp.start('css:build');
    });
    watch([path.watch.js], function(event, cb) {
        gulp.start('js:build');
    });
    watch([path.watch.img], function(event, cb) {
        gulp.start('image:build');
    });
    watch([path.watch.fonts], function(event, cb) {
        gulp.start('fonts:build');
    });
});

gulp.task('webserver', function() {
    browserSync(config);
});

gulp.task('clean', function(cb) {
    rimraf(path.clean, cb);
});

gulp.task('default', ['build', 'webserver', 'watch']);

but he took something and stopped working... says
"task function must be specified"
before everything worked..
This is how my package.json looks like

{
  "name": "testgulp",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "dependencies": {
    "browser-sync": "^2.2.3",
    "gulp": "latest",
    "gulp-autoprefixer": "^2.1.0",
    "gulp-clean-css": "latest",
    "gulp-imagemin": "^2.2.1",
    "gulp-sass": "latest",
    "gulp-sourcemaps": "^1.5.0",
    "gulp-uglify": "^1.1.0",
    "gulp-watch": "^4.1.1",
    "imagemin-pngquant": "^4.0.0",
    "main-bower-files": "^2.13.1",
    "rimraf": "^2.3.1"
  },
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC"
}

there are only 2 overrides in bower.json - the rest is standard:

"overrides":
    {
        "bootstrap":
        {
            "main": [
                "./dist/js/bootstrap.min.js",
                "./dist/css/bootstrap.min.css"
            ]
        },
        "jquery":
        {
            "main": "dist/jquery.min.js"
        }
    }

npm version - 6.4.1
bower version - 1.8.4
gulp version:
CLI version 2.0.1
Local version 4.0.0
Please help)

Answer 1

Somewhere in the middle of summer (2018) compiled my galp file

Most likely this is exactly the point. Couldn't wait for autumn?
we hardly know each other, and you already show your package.json
this is all because it is new: https://www.liquidlight.co.uk/blog/article/how-do-...
namely:
it was in the old version:

gulp.task('default', ['del'], function() {
    // default task code here
});

became:

gulp.task('default', gulp.series('del', function() { 
    // default task code here
}));