Why are there errors when deploying a site through Travis?

Question

Node.js

Good afternoon. Previously I worked with gulp and deployed sites to gh-pages via travis and had no problems, only if the tests did not pass. Now I switched to Gulp 4 in the assembly and the following errors began to appear during the deployment:

Here is the package.json file:

{
  "name": "template",
  "private": false,
  "description": "My work template",
  "author": "Vashkevich Dmitrii",
  "license": "ISC",
  "devDependencies": {
    "@htmlacademy/editorconfig-cli": "1.x",
    "browser-sync": "^2.26.14",
    "del": "^6.0.0",
    "eslint": "4.16.0",
    "eslint-config-htmlacademy": "0.4.x",
    "gulp": "^4.0.2",
    "gulp-autoprefixer": "^7.0.1",
    "gulp-concat": "^2.6.1",
    "gulp-imagemin": "^7.1.0",
    "gulp-newer": "^1.4.0",
    "gulp-plumber": "^1.2.1",
    "gulp-pug": "^4.0.1",
    "gulp-sass": "^4.1.0",
    "gulp-sourcemaps": "^3.0.0",
    "gulp-svg-sprite": "^1.5.0",
    "gulp-ttf2woff": "^1.1.1",
    "gulp-ttf2woff2": "^4.0.1",
    "gulp-uglify-es": "^2.0.0",
    "pug-lint": "^2.6.0",
    "stylelint": "10.1.x",
    "stylelint-config-htmlacademy": "^0.1.4"
  },
  "scripts": {
    "editorconfig": "editorconfig-cli",
    "stylelint": "stylelint \"src/scss/**/*.scss\" --syntax scss",
    "test": "npm run editorconfig && npm run stylelint && eslint src/scripts/",
    "build": "gulp build",
    "start": "gulp"
  },
  "editorconfig-cli": [
    "*.json",
    "*.js",
    "src/*.pug",
    "src/scripts/**/*.js",
    "src/images/**/*.svg",
    "src/scss/**/*.sсss"
  ],
  "engines": {
    "node": "8.16"
  }
}

travis file:

language: node_js

node_js:
  - "8.16"

before_deploy:
  - npm run build
  - echo -e "node_modules\npackage-lock.json" > .gitignore

deploy:
  provider: pages
  skip-cleanup: true
  local_dir: build
  github-token: $GITHUB_TOKEN
  keep-history: true
  on:
    branch: main

notifications:
  email: false

I will be grateful for any help.
PS If you have an alternative solution for deploying to gh-pages, so as not to push the build folder to the main branch, but keep only the sources there, and upload the build to gh-pages, I will be doubly grateful.