Alguém poderia me ajudar a resolver o seguinte erro que aparece ao tentar usar o gulp useref?
assert.js:339 throw err; ^
AssertionError [ERR_ASSERTION]: Task function must be specified at Gulp.set [as setTask] (C:\Users\cmtsi\AppData\Local\Google\Cloud SDK\projeto\performance-web\nodemodules\undertaker\lib\set-task.js:10:3) at Gulp.task (C:\Users\cmtsi\AppData\Local\Google\Cloud SDK\projeto\performance-web\node_modules\undertaker\lib\task.js:13:8) at Object. (C:\Users\cmtsi\AppData\Local\Google\Cloud SDK\projeto\performance-web\gulpfile.js:88:6) at Module.compile (internal/modules/cjs/loader.js:778:30) at Object.Module.extensions..js (internal/modules/cjs/loader.js:789:10) at Module.load (internal/modules/cjs/loader.js:653:32) at tryModuleLoad (internal/modules/cjs/loader.js:593:12) at Function.Module._load (internal/modules/cjs/loader.js:585:3) at Module.require (internal/modules/cjs/loader.js:692:17) at require (internal/modules/cjs/helpers.js:25:18)