A potential feature request…
If you use the Execute Macro block (runs another macro from within a macro) but then delete the macro that is being executed in that block, the Execute Macro event remains but its contents are now silently cleared out, potentially breaking functionality that the user is unaware of.
It might be nice if Keyboard Maestro could traverse your macro library when the user attempts to delete a macro, and check for the existence of any dependencies on a macro (such as the case above where it is being called from another macro) and pop up a confirmation dialog box informing the user that the macro is being referenced elsewhere, and are they sure they want to delete it with OK/Cancel buttons.