How to determine why a spellcast failed

[Lodran]

I'm working on a plugin that implements a blacklist functionality when casting spells.

Unfortunately, right now it blacklists units for reasons that it shouldn't - for example, when you are stunned, silenced or out of mana.

So, when my SPELLCAST_FAILED event is called, how can I determine why the spell failed, so that I can avoid blacklisting players for stupid reasons?

[Esamynn]

You could monitor the UI_ERROR_MESSAGE event, which is the event responsible for displaying the red error messages in the middle of your screen. You can then check what the error message was and filter based on that.