If you have ever developed a plugin for WordPress you may remember seeing one of those unhelpful messages saying your plugin generated N characters of unexpected output.
The problem with those messages, apart from not knowing what exactly is what your plugin generated, is that sometimes the errors are not easy to reproduce. You go to your Plugins section, deactivate the plugin in question, try to activate it again and now all you see is “Plugin activated”, no errors.
The last time that happened to me I decided I wanted to see the content of those errors every time they occurred, and I came up with a solution to achieve just that. Is not pretty, but it works. Basically, I stop WordPress execution when this errors occur and show the output in my screen: