Only attempt to decrypt custom fields in activity log if the value is not empty

[snipe]

This just cuts down a bit on the extra debug logging by only attempting the try { if there's actually a value for the field. (Nothing to decrypt otherwise.)

[what-the-diff]

PR Summary

• Improved Error Handling in ActionlogsTransformer.php
  A more robust conditional check has been added to a transform operation in ActionlogsTransformer.php, ensuring that it only proceeds if required data exists. This enhances the application's stability by reducing the chance of encountering unexpected errors.

• Enhanced Error Messaging
  Error messages have been refined in ActionlogsTransformer.php, providing clearer indications when an issue arises, such as undecipherable data due to potential changes in encryption keys.

• Removal of Redundant Debug Log
  A superfluous debug log, "custom fields do not match," has been removed, simplifying the debugging process by reducing irrelevant information.

• Better Security Measures for Meta Data
  In the event of a mismatch between old and new encrypted data, the related meta data is now hidden and replaced with "************". This strengthens the security by ensuring sensitive encrypted information isn't inadvertently exposed.