fix iterating on dead entities after player dies

assets/levels/01-friendly-obstacles.lvl

@@ -4,11 +4,11 @@ Background: background-lila
                     
                     
    #############    
-   #           #    
+   #     t     #    
    #>  S #     #    
-   #    >#    >#    
-   #<    #     #    
-   #    v#    <#    
+   #    >#    ^#    
+   #<    #W#####    
+   # o  v#    o#    
    #############    
                     
                     

systems/destroyable_system.go

@@ -60,6 +60,10 @@ func (system *DestroyableSystem) Update() error {
 		doorposition, renderable, door := query.Get()
 
 		for player := range playerobserver.Entities {
+			if !system.World.Alive(player) {
+				continue
+			}
+
 			playerposition := (*Position)(system.World.Get(player, posID))
 			playervelocity := (*Velocity)(system.World.Get(player, veloID))
 

systems/transient_system.go

@@ -60,6 +60,10 @@ func (system *TransientSystem) Update() error {
 		transientposition, _, transient := query.Get()
 
 		for player := range playerobserver.Entities {
+			if !system.World.Alive(player) {
+				continue
+			}
+
 			playerposition := (*Position)(system.World.Get(player, posID))
 			playervelocity := (*Velocity)(system.World.Get(player, veloID))