HandlenetServiceBean must not catch Throwables

[bencomp]

SonarQube found some issues that must be addressed immediately, among which are four violations of the rule "Throwable and Error should not be caught", all found in HandlenetServiceBean.

Rationale:

Throwable is the superclass of all errors and exceptions in Java.
Error is the superclass of all errors, which are not meant to be caught by applications.
Catching either Throwable or Error will also catch OutOfMemoryError and InternalError, from which an application should not attempt to recover.
Only Exception and its subclasses should be caught.

[pdurbin]

Closing to consolidate into #3950.

[bencomp]

Triggered by #9846, I notice that Sonarcloud does not mark this still existing issue as problematic.