Issue 11813 & 11814 - improve diagnostic messages on IFTI failure

[Issue 11813](https://d.puremagic.com/issues/show_bug.cgi?id=11813) - Improve IFTI error diagnostic
[Issue 11814](https://d.puremagic.com/issues/show_bug.cgi?id=11814) - Unnecessary error messages "does not match ..." on IFTI failure