This is Wings reporting that the game process stopped. Scroll up to the first relevant failure and record the exit code and out-of-memory flag from the same attempt.
Identify why the process stopped
With Out of memory true, compare the container memory limit with Java -Xmx. Java also uses memory outside the heap. Code 137 alone does not prove OOM. When the flag is false, check for termination from the host or panel as well.
journalctl -u wings --since "15 minutes ago" --no-pager
For code 0 with OOM false, check the startup command, JAR name and the reason for the clean exit. With code 1, the earlier exception often identifies Java compatibility, configuration or a plugin. If you administer the host, read the Wings journal for the same period.
Change one thing and start it again. After a complete startup, test a game login and a planned stop. The restart policy only controls what happens after the process exits.