TypeError: Cannot read property 'serve:before' of undefined on Ionic CLI 2.2.1 + Gulp 4 - ionic2

Question

I am developing a Web Application that have a lot of legacy dependencies.
On the trial of updating some packages, I updated the gulp/gulpfile.js and tinkered then to run. Gulp was on version 3.5 and now is on 4.0.
By the way, the error thrown in the terminal by running : ionic serve --address localhost --nobrowser is :
Error: spawn cordova EACCES
at Process.ChildProcess._handle.onexit (internal/child_process.js:240:19)
at onErrorNT (internal/child_process.js:415:16)
at process._tickCallback (internal/process/next_tick.js:63:19)
at Function.Module.runMain (internal/modules/cjs/loader.js:834:11)
at startup (internal/bootstrap/node.js:283:19)
at bootstrapNodeJSCore (internal/bootstrap/node.js:622:3)
Mind letting us know? https://github.com/driftyco/ionic-cli/issues
******************************************************
Dependency warning - for the CLI to run correctly,
it is highly recommended to install/upgrade the following:
Please update your Cordova CLI to version >=4.2.0 `npm install -g cordova`
******************************************************
TypeError: Cannot read property 'serve:before' of undefined
at Object.runWithGulp (/usr/lib/node_modules/ionic/lib/cli.js:237:17)
at Object.runr (/usr/lib/node_modules/ionic/lib/cli.js:194:18)
at /usr/lib/node_modules/ionic/lib/cli.js:54:9
at _fulfilled (/usr/lib/node_modules/ionic/node_modules/q/q.js:787:54)
at /usr/lib/node_modules/ionic/node_modules/q/q.js:816:30
at Promise.promise.promiseDispatch (/usr/lib/node_modules/ionic/node_modules/q/q.js:749:13)
at /usr/lib/node_modules/ionic/node_modules/q/q.js:557:44
at flush (/usr/lib/node_modules/ionic/node_modules/q/q.js:108:17)
at process._tickCallback (internal/process/next_tick.js:61:11)
Cannot read property 'serve:before' of undefined (CLI v2.2.1)
Your system information:
Cordova CLI: undefined
Ionic CLI Version: 2.2.1
Ionic App Lib Version: 2.2.0
ios-deploy version: Not installed
ios-sim version: Not installed
OS: Linux 5.4
Node Version: v10.16.3
Xcode version: Not installed
Then, some patch of the gulpfile.js :
gulp.task('build', gulp.series('bundle', 'copyTask', 'revTask', 'revReplaceTask'));
gulp.task('default', gulp.series('sassTask', 'cleanTask', 'build', 'watchTask'));
gulp.task('serve:before', gulp.series('cleanTask', 'watchTask', 'build'));
Before the tinkering, gulp.task('serve:before' [...]) functioned well. I guess it is related with the Ionic 2.2.1 CLI.
If someone could help me by a hint or an advice for mismatching the problem, I would be glad.

Answer 1

This happened to me while I upgraded Node to v12 which forced me to upgrade Gulp to v4.
The solution that worked for me is:
Go to npm\node_modules\ionic\lib\cli.js (Wherever it's located).
Change the following lines as such in cli.js:
237: if (true || gulp.tasks[beforeHook]) {
257: if (true || gulp.tasks[afterHook]) {
270: return Q.nfcall(null/*gulp.start.bind(gulp)*/, hookName)
Basically, the reason is that gulp.tasks and gulp.start don't exist in Gulp v4.
By putting true || in the first occurrences, gulp.tasks won't run and by putting null in the last occurrence, the gulp.start won't run.
I hope this helps the next people that encounter this problem.