I found few errors in incbin utility.
1) ret flag not initialized to zero at startup. Therefore, utility can never terminate correctly. I dont know, why you not found this bug before: it always deletes output file in last step. This has also mentioned here: https://github.com/graphitemaster/incbin/issues/39
2) ret flag is not set, if utility can not read input binary.
I found few errors in incbin utility. 1) ret flag not initialized to zero at startup. Therefore, utility can never terminate correctly. I dont know, why you not found this bug before: it always deletes output file in last step. This has also mentioned here: https://github.com/graphitemaster/incbin/issues/39
2) ret flag is not set, if utility can not read input binary.