RFR: JDK-8266918: merge_stack in check_code.c add NULL check [v2]

[Christoph Langer]

On Fri, 4 Jun 2021 14:10:20 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>> Hello, please review this small Sonar finding.
>> Sonar reports a potential NULL pointer dereference here :
>> https://sonarcloud.io/project/issues?id=shipilev_jdk&languages=c&open=AXck8CPLBBG2CXpcnh_z&resolved=false&severities=MAJOR&types=BUG
>> "Access to field 'item' results in a dereference of a null pointer (loaded from variable 'new')"
>> It would be better to add a check .
>
> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Replace check by assertion

Marked as reviewed by clanger (Reviewer).

-------------

PR: https://git.openjdk.java.net/jdk/pull/3979