Should be great if on debug a stacktrace (like on the "whoops" page) we have a visual difference between the "vendor code" and the "application code". It can help find out "where my problem starts".

The ReflectionClass() should help to tell where file is located, then just check if it is from "vendor" folder to mark as "white background" else "yellow background" to indicate an "user-zone file".

Example: