Fix "eating of exception" introduced in PR #839

[thomas-boehm-tractive]

Jenkins and plugins versions report

Environment

Jenkins: 2.387.3
OS: Linux - 4.14.336-257.568.amzn2.x86_64
Java: 11.0.19 - Eclipse Adoptium (OpenJDK 64-Bit Server VM)  

What Operating System are you using (both controller, and any agents involved in the problem)?

Controller running in docker

Reproduction steps

#839 introduced the issue that exceptions of the callable are no longer forwarded, but "eaten" by a try-catch block.

Expected Results

Exceptions should be thrown, as before.

Actual Results

null is returned -> no exception thrown and logged

Anything else?

No response

Are you interested in contributing a fix?

A PR will be created and linked.

[thomas-boehm-tractive]

Related to ticket #838, where this bug was introduced.

[thomas-boehm-tractive]

Issue was discussed here: #839 (review)