Add null check for fireworks tag (Closes #636)

connector/src/main/java/org/geysermc/connector/network/translators/item/translators/nbt/FireworkTranslator.java

@@ -36,10 +36,15 @@ public class FireworkTranslator extends NbtItemStackTranslator {
 
     @Override
     public void translateToBedrock(CompoundTag itemTag, ItemEntry itemEntry) {
-        CompoundTag fireworks = itemTag.get("Fireworks");
+        if (!itemTag.contains("Fireworks")) {
+            return;
+        }
 
+        CompoundTag fireworks = itemTag.get("Fireworks");
         ListTag explosions = fireworks.get("Explosions");
-        if (explosions != null) {
+        if (explosions == null) {
+            return;
+        }
         for (Tag effect : explosions.getValue()) {
             CompoundTag effectData = (CompoundTag) effect;
 
@@ -85,7 +90,6 @@ public class FireworkTranslator extends NbtItemStackTranslator {
             explosions.add(newEffectData);
         }
     }
-    }
 
     @Override
     public void translateToJava(CompoundTag itemTag, ItemEntry itemEntry) {