fcl-hash / fcl-css: add special exception class?

In the 'fcl-hash' & 'fcl-css' dirs I have found many lines which raise the exception. Like this

raise Exception.Create('20220428160853');

I suggest to add special class for hash-related exceptions / css-parser exceptions. To catch such errors by checking the exception-class.

In fcl-css, such classes exist:

 ECSSException = class(Exception);
ECSSScanner = Class(ECSSException);

but are not used everywhere. it's OK?