Process "crashed" and test fails when closing the application in test

Have a look at the sample code shown here https://support.smartbear.com/testcomplete/docs/testing-with/tested-apps/closing.html 

If you manually close your application, does it close without crashing?

What version of TestComplete are you using?

TestComplete includes the DbgServices plugin that lets you run tested applications in the Debug mode, see https://support.smartbear.com/testcomplete/docs/testing-with/advanced/tracing-critical-errors/about.html 

Maybe your application hasn't finished loading when you attempt to close it?  Can you add another Wait method to confirm the application has finished loading?  For instance, we use a WaitWindow to detect that our start window has opened.  Other options might be a WaitProperty to verify the application window is enabled, or WaitProperty for a toolbar button to become enabled.

It seems like a timing issue could be the culprit.  Just because WaitProcess determines the EXE is running doesn't mean the app is ready for interaction via automation or the user interface.