Currently clicking on stop button only calls GeneralEvents_OnStopTest but at that moment inside of GeneralEvents_OnStopTest Log.ErrCount is not raised by 1 because the Message "The script execution was interrupted" is only logged after GeneralEvents_OnStopTest is finished.
Please add the possibility to catch the case "The script execution was interrupted" before GeneralEvents_OnStopTest is called (maybe a new Event GeneralEvents_OnStopButtonClicked) or raise Log.ErrCount by 1 before GeneralEvents_OnStopTest is called
Here is also a thread i opened where the problem is explained:
https://community.smartbear.com/t5/TestComplete-Questions/No-Log-ErrCount-when-test-is-being-stopped-manually/td-p/250202