[ALICE3] fix bug in a3 cascade finding

[jesgum]

No description provided.

[github-actions]

O2 linter results: ❌ 5 errors, ⚠️ 0 warnings, 🔕 0 disabled

[alibuild]

Auto-approving on behalf of @jesgum.

[alibuild]

Error while checking build/O2Physics/code-check for 5e87226 at 2026-07-10 17:15:

## sw/BUILD/O2Physics-code-check-latest/log
--
========== List of issues found ==========
++ echo 'Found 2 errors and 3 warnings.'
Found 2 errors and 3 warnings.
++ [[ 2 -gt 0 ]]
++ cat /sw/BUILD/f33a5d40a88b7dac77309eb589294c9486ff7c0e/O2Physics-code-check/errors.txt
ALICE3/TableProducer/alice3strangenessFinder.cxx:72:8: error: constructor does not initialize these fields: pdgDB [cppcoreguidelines-pro-type-member-init,-warnings-as-errors]
ALICE3/TableProducer/alice3strangenessFinder.cxx:420:7: error: do not use 'else' after 'return' [readability-else-after-return,-warnings-as-errors]
++ [[ 3 -gt 0 ]]
++ cat /sw/BUILD/f33a5d40a88b7dac77309eb589294c9486ff7c0e/O2Physics-code-check/warnings.txt
ALICE3/TableProducer/alice3strangenessFinder.cxx:686:35: warning: statement should be inside braces [readability-braces-around-statements]
ALICE3/TableProducer/alice3strangenessFinder.cxx:688:42: warning: statement should be inside braces [readability-braces-around-statements]
ALICE3/TableProducer/alice3strangenessFinder.cxx:701:80: warning: statement should be inside braces [readability-braces-around-statements]
++ [[ 2 -gt 0 ]]
++ exit 1
--

Full log here.