fix: ConcurrentModificationException in validateUpgradeTier crashes addon on load

[Copilot]

Addon fails to load when any upgrade tier references a missing upgrade data entry (e.g. after partial seeding or manual data corruption). validateUpgradeTier() called HashMap.remove() inside a values().forEach() loop over the same map, throwing ConcurrentModificationException and aborting the entire addon startup.

Fix

Replace the unsafe iteration+removal pattern with entrySet().removeIf():

// Before — throws ConcurrentModificationException
this.upgradeTierCache.values().forEach(tier -> {
    if (!this.upgradeDataCache.containsKey(tier.getUpgrade())) {
        this.upgradeTierCache.remove(tier.getUniqueId()); // structural mod during iteration
    }
});

// After — safe
this.upgradeTierCache.entrySet().removeIf(entry -> {
    if (!this.upgradeDataCache.containsKey(entry.getValue().getUpgrade())) {
        this.addon.logWarning("Upgrade tier " + entry.getValue().getUniqueId()
            + " has a reference to an unknown upgrade data. It will be skipped");
        return true;
    }
    return false;
});

Also corrects two typos in the warning message (unknow → unknown, skiped → skipped).

Tests

Adds UpgradesDataManagerTest with three cases: single orphaned tier removed without exception, valid tier preserved, and multiple simultaneous orphans removed — covering the exact reported scenario (Boxed_example_range2_t1, Boxed_example_diamond_t1).

[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