Webdriverio: Advice on how to fail a test if there are javascript errors

This seems to me to be a very basic use case. I believe the .Net selenium suite has an option for it. In PHP and Codeception, I attach to every "Step" which is like every command in wdio be it waitFor* or getText or url() and each step I check for errors that have bubbled up to window.onerror. Is there a way to run a function at every step in wdio?

I suppose it would be possible to do something like:

window.onerror = function () {
document.write('');
}

That would cause the next step to fail. But that seems slightly unreliable.
This of course would coincide with the command:

beforeSuite(() => browser.execute(...));

Is there a way to run a function at every step in wdio?

Yes, the wdio testrunner has a afterCommand hook to do this.

Join our for these kind of questions. This is not necessary an issue.

Perfect thank you! I'll post back with my solution to make it fail the test
and maybe we can get the use case in the docs!!

Any suggestion on how to fail a test if there are errors?

I tried the chat and was ignored.

This is an issue because this is a very common use case and its entirely undocumented.

Here is what I came up with for the javascript error checker that I used on another site and Codeception, works with Angular and wdio now:

    beforeCommand: function (commandName, args) {
        if (browser.getUrl().indexOf(this.baseUrl) > -1) {
            browser.execute(function () {
                if (window.wdioErrorHandler !== window.onerror) {
                    const oldHandler = window.onerror;
                    window.windowErrors = [];
                    window.onerror = window.wdioErrorHandler = function (err) {
                        window.windowErrors.push(err + '');
                        if (typeof oldHandler === 'function') {
                            oldHandler.apply(this, arguments);
                        }
                    }
                }
            })
        }
    },

    afterCommand: function (commandName, args, result, error) {
        if (browser.getUrl().indexOf(this.baseUrl) > -1) {
            const errors = browser.execute(function () {
                return window.windowErrors;
            });
            if (errors.value !== null && errors.value.length > 0) {
                throw new Error('Javascript errors! ' + errors.value);
            }
        }
    }

How do I intentionally fail a command from the afterCommand block? I need the test to fail, but even with the throw in there it still says the test passes.

Is there somewhere in the docs we could put some examples on how to use hooks? Maybe in the debugging section?

This search doesn't really show anything helpful: https://www.google.com/search?q=wdio+hooks+example