fix: resolve nil value errors in handleGuildWar function

[omarcopires]

Description

I made corrections to the death.lua script to resolve nil value errors in the handleGuildWar function. I added checks to ensure that both the player and the killer are valid and that both belong to a guild before proceeding with the guild war logic. This helps prevent failures when one of the objects is undefined.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I checked the PR checks reports
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud