Running gulp does not compile files from /assets/css to /assets/built

[konomu]

Running gulp in my cloned repo gives

AssertionError [ERR_ASSERTION]: Task function must be specified
    at Gulp.set [as _setTask] (/home/konomu/jasper2-personal/node_modules/undertaker/lib/set-task.js:10:3)
    at Gulp.task (/home/konomu/jasper2-personal/node_modules/undertaker/lib/task.js:13:8)
    at Object.<anonymous> (/home/konomu/jasper2-personal/gulpfile.js:27:6)
    at Module._compile (node:internal/modules/cjs/loader:1356:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1414:10)
    at Module.load (node:internal/modules/cjs/loader:1197:32)
    at Module._load (node:internal/modules/cjs/loader:1013:12)
    at Module.require (node:internal/modules/cjs/loader:1225:19)
    at require (node:internal/modules/helpers:177:18)
    at requireOrImport (/usr/local/lib/node_modules/gulp-cli/lib/shared/require-or-import.js:20:11) {
  generatedMessage: false,
  code: 'ERR_ASSERTION',
  actual: false,
  expected: true,
  operator: '=='
}

and css is not built from /assets/css to /assets/built. The problem seems to be a change the way gulp handles tasks itself per https://stackoverflow.com/questions/51098749/everytime-i-run-gulp-anything-i-get-a-assertion-error-task-function-must-be
but I don't know how to solve this issue on my own.