The Error Checker looks for setup errors as you edit FSMs. This allows you to catch and fix errors before you even hit play.
The checker shows errors at a different levels in the UI so you can follow the indicators to pinpoint the exact location of the error.
1. An Error Count in the Debugging Toolbar:
Clicking on the Error Count opens the Error Check Window.
2. Error Icons in the Graph View, Fsm Browser, Template Browser and State Browser.
3. Error Boxes in Action Editors.
NOTE: Some error boxes are clickable, letting you automatically fix the error!
For example, clicking the the error box above adds an AudioSource Component to the GameObject.