Magento Debugging Horror!
Changing lots of things in magento with no problem. Continuing development for quite sometime. Suddenly decide to clear cache to see affect of a change on a template in frontent. Suddenly magento crashes! There's no error message. No exception log. No log in any file anywhere on the disk. All that happens is that magento suddenly returns you to the home page!
Reverting all the changes to the template. Clear the cache. Nope! Still the same! Why? Because the problem has happened somewhere in your code. Magento just didn't face it, because it was using an older version of your code. How? Because magento 2 even caches code! Not the php opcache. Don't get me wrong. It has it's own cache for code, in a folder called generated. Now that you cleared all the caches including this folder, you just realized that, somewhere something is wrong. But there is no way for you to know where as there is absolutely no exception logged anywhere!
So you debug the code, from index.php, down to the deepest levels of hell. In a normal php code, once the exception happens, you should see the control jumps to an exception handler, there, you can see the exception object and its call stack in your debugger. But that's not the case with magento.
Your debugger suddenly jumps to a function named:
write_close();
That's all. No exception object. No call stack. No way to figure out why it failed. So you decide to debug into each and every step to figure out where it crashes. The way magento renders response to each request is that, it calls a plugin, which calls a plugin loop, which calls another plugin, which calls a list of plugins, which calls a plugin loop, which calls another plugin.....
And if in each step, just by accident, instead of step through, you use the step over command of your debugger, the crash happens suddenly and you end up with the same freaking write_close() function with no idea what went wrong and where the error happened! You spend a whole day, to figure out, that this is actually a bug in core of magento, they simply introduced after your recent update of magento core to the latest STABLE version!!! It was not your mistake. They ruined their own code for the thousandth of time. You just didn't notice it, because as I said, you didn't clear the `generated` folder, therefore using an older version of everything!
Now that after spending 7 hours figuring out what has failed with absolutely no standard way of debugging and within a spaghetti of GOTO commands (Magento calls them plugin), why not report it to github? So you report it with a pull request. This also takes 1 hour of your time. Just to next day get informed that your pull request is rejected because another person already fixed the bug and made the same pull request. It was just not on the latest stable version yet!
So you decide to avoid updating magento as much as possible. Because you know that the next Stable version will make your life and career unstable. But then the customer complains that the Admin Panel is warning him of using old Magento version which might pose SECURITY THREATS!