added broken damage listener and registered it

src/main/java/de/steev/bm/BetterMinecraft.java

@@ -2,6 +2,7 @@ package de.steev.bm;
 
 import de.steev.bm.Commands.back;
 import de.steev.bm.Listener.BedListener;
+import de.steev.bm.Listener.DamageListener;
 import de.steev.bm.Listener.InteractListener;
 import de.steev.bm.Listener.KillListener;
 import de.steev.bm.Manager.GameManager;
@@ -47,6 +48,7 @@ public class BetterMinecraft extends JavaPlugin implements Listener {
 		this.getServer().getPluginManager().registerEvents(new BedListener(this.gameManager), this);
 		this.getServer().getPluginManager().registerEvents(new KillListener(this.gameManager), this);
 		this.getServer().getPluginManager().registerEvents(new InteractListener(this.gameManager), this);
+		this.getServer().getPluginManager().registerEvents(new DamageListener(this.gameManager), this);
 		this.getServer().getPluginManager().registerEvents(this, this);
 
 		this.getCommand("back").setExecutor(new back(this.gameManager));

src/main/java/de/steev/bm/Listener/DamageListener.java

@@ -0,0 +1,25 @@
+package de.steev.bm.Listener;
+
+import de.steev.bm.Manager.GameManager;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.entity.EntityDamageByEntityEvent;
+
+public class DamageListener implements Listener {
+
+    private GameManager gameManager;
+
+    public DamageListener(GameManager gameManager) {
+        gameManager.getPlugin().getLogger().info("Damage Listener Registered");
+        this.gameManager = gameManager;
+    }
+
+    @EventHandler
+    public void onEntityDamageByEntity(EntityDamageByEntityEvent event) {
+        if((event.getEntity() instanceof Player player)) {
+            event.setCancelled(true);
+            player.damage(event.getFinalDamage());
+        }
+    }
+}

src/main/java/de/steev/bm/Listener/InteractListener.java

@@ -26,6 +26,7 @@ public class InteractListener implements Listener {
             /** the clicked block */
             Block target = event.getClickedBlock();
             /** the location of the clicked block */
+            assert target != null;
             Location loc = target.getLocation().clone().add(0.5, 0.5, 0.5);
             Material[] drops;
             int[] amounts;