fix: json.Unmarshal not resetting struct fields (#345)

The json.Unmarshal function was not properly resetting the Stats struct fields between iterations in the loop. This caused incorrect values to be retained from previous iterations, leading to unexpected behavior.

This commit fixes the issue by zero the struct in each loop iteration, ensures that each unmarshaling operation starts with a clean struct, preventing value carryover.

beszel/internal/records/records.go

@@ -155,6 +155,7 @@ func (rm *RecordManager) AverageSystemStats(records RecordStats) system.Stats {
 
 	var stats system.Stats
 	for i := range records {
+		stats = system.Stats{} // Zero the struct before unmarshalling
 		json.Unmarshal(records[i].Stats, &stats)
 		sum.Cpu += stats.Cpu
 		sum.Mem += stats.Mem