Some minor touch-ups

proxy/src/main/java/com/velocitypowered/proxy/protocol/ProtocolUtils.java

@@ -18,6 +18,8 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;
 
+import io.netty.handler.codec.DecoderException;
+import io.netty.handler.codec.EncoderException;
 import net.kyori.nbt.CompoundTag;
 
 public enum ProtocolUtils {
@@ -196,22 +198,21 @@ public enum ProtocolUtils {
     int indexBefore = buf.readerIndex();
     byte startType = buf.readByte();
     if (startType == 0) {
-      return null;
-    } else {
-      buf.readerIndex(indexBefore);
-      try {
-        DataInput input = new ByteBufInputStream(buf);
-        byte type = input.readByte();
-        if (type != 10) {
-          return null;
-        }
-        input.readUTF();
-        CompoundTag ret = new CompoundTag();
-        ret.read(input, 0);
-        return ret;
-      } catch (IOException e) {
-        return null;
+      throw new DecoderException("Invalid NBT start-type (end/empty)");
+    }
+    buf.readerIndex(indexBefore);
+    try {
+      DataInput input = new ByteBufInputStream(buf);
+      byte type = input.readByte();
+      if (type != 10) {
+        throw new DecoderException("NBTTag is not a CompoundTag");
       }
+      input.readUTF(); // Head-padding
+      CompoundTag compoundTag = new CompoundTag();
+      compoundTag.read(input, 0);
+      return compoundTag;
+    } catch (IOException e) {
+      throw new DecoderException("Unable to decode NBT CompoundTag at " + indexBefore);
     }
   }
 
@@ -223,15 +224,15 @@ public enum ProtocolUtils {
   public static void writeCompoundTag(ByteBuf buf, CompoundTag compoundTag) {
     if (compoundTag == null) {
       buf.writeByte(0);
-    } else {
-      try {
-        DataOutput output = new ByteBufOutputStream(buf);
-        output.writeByte(10);
-        output.writeUTF("");
-        compoundTag.write(output);
-      } catch (IOException e) {
-        e.printStackTrace();
-      }
+      return;
+    }
+    try {
+      DataOutput output = new ByteBufOutputStream(buf);
+      output.writeByte(10); // Type 10 - CompoundTag
+      output.writeUTF(""); // Head-padding
+      compoundTag.write(output);
+    } catch (IOException e) {
+      throw new EncoderException("Unable to encode NBT CompoundTag");
     }
   }
 

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/Chat.java

@@ -20,7 +20,7 @@ public class Chat implements MinecraftPacket {
 
   private @Nullable String message;
   private byte type;
-  private UUID sender;
+  private @Nullable UUID sender;
 
   public Chat() {
   }
@@ -72,7 +72,7 @@ public class Chat implements MinecraftPacket {
     message = ProtocolUtils.readString(buf);
     if (direction == ProtocolUtils.Direction.CLIENTBOUND) {
       type = buf.readByte();
-      if(version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+      if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
         sender = ProtocolUtils.readUuid(buf);
       }
     }
@@ -87,7 +87,7 @@ public class Chat implements MinecraftPacket {
     if (direction == ProtocolUtils.Direction.CLIENTBOUND) {
       buf.writeByte(type);
       if(version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
-        ProtocolUtils.writeUuid(buf, sender == null ? new UUID(0,0) : sender);
+        ProtocolUtils.writeUuid(buf, sender == null ? EMPTY_SENDER : sender);
       }
     }
   }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/JoinGame.java

@@ -17,14 +17,14 @@ public class JoinGame implements MinecraftPacket {
   private short difficulty;
   private short maxPlayers;
   private @Nullable String levelType;
-  private int viewDistance; //1.14+
+  private int viewDistance; // 1.14+
   private boolean reducedDebugInfo;
   private boolean showRespawnScreen;
-  private boolean shouldKeepPlayerData;
-  private boolean isDebug;
-  private boolean isFlat;
-  private String dimensionRegistryName;
-  private CompoundTag dimensionRegistry;
+  private boolean shouldKeepPlayerData; // 1.16+
+  private boolean isDebug; // 1.16+
+  private boolean isFlat; // 1.16+
+  private String dimensionRegistryName; // 1.16+
+  private CompoundTag dimensionRegistry; // 1.16+
 
   public int getEntityId() {
     return entityId;
@@ -149,6 +149,10 @@ public class JoinGame implements MinecraftPacket {
         + ", levelType='" + levelType + '\''
         + ", viewDistance=" + viewDistance
         + ", reducedDebugInfo=" + reducedDebugInfo
+        + ", shouldKeepPlayerData=" + shouldKeepPlayerData
+        + ", isDebug=" + isDebug
+        + ", isFlat='" + isFlat
+        + ", dimensionRegistryName='" + dimensionRegistryName + '\''
         + '}';
   }
 
@@ -159,12 +163,10 @@ public class JoinGame implements MinecraftPacket {
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
       this.dimensionRegistry = ProtocolUtils.readCompoundTag(buf);
       this.dimensionRegistryName = ProtocolUtils.readString(buf);
+    } else if (version.compareTo(ProtocolVersion.MINECRAFT_1_9_1) >= 0) {
+      this.dimension = buf.readInt();
     } else {
-      if (version.compareTo(ProtocolVersion.MINECRAFT_1_9_1) >= 0) {
-        this.dimension = buf.readInt();
-      } else {
-        this.dimension = buf.readByte();
-      }
+      this.dimension = buf.readByte();
     }
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_13_2) <= 0) {
       this.difficulty = buf.readUnsignedByte();
@@ -198,12 +200,10 @@ public class JoinGame implements MinecraftPacket {
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
       ProtocolUtils.writeCompoundTag(buf, dimensionRegistry);
       ProtocolUtils.writeString(buf, dimensionRegistryName);
+    } else if (version.compareTo(ProtocolVersion.MINECRAFT_1_9_1) >= 0) {
+      buf.writeInt(dimension);
     } else {
-      if (version.compareTo(ProtocolVersion.MINECRAFT_1_9_1) >= 0) {
-        buf.writeInt(dimension);
-      } else {
-        buf.writeByte(dimension);
-      }
+      buf.writeByte(dimension);
     }
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_13_2) <= 0) {
       buf.writeByte(difficulty);

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/Respawn.java

@@ -13,10 +13,10 @@ public class Respawn implements MinecraftPacket {
   private short difficulty;
   private short gamemode;
   private String levelType = "";
-  private boolean shouldKeepPlayerData;
-  private boolean isDebug;
-  private boolean isFlat;
-  private String dimensionRegistryName;
+  private boolean shouldKeepPlayerData; // 1.16+
+  private boolean isDebug; // 1.16+
+  private boolean isFlat; // 1.16+
+  private String dimensionRegistryName; // 1.16+
 
   public Respawn() {
   }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/ArgumentPropertyRegistry.java

@@ -134,6 +134,6 @@ public class ArgumentPropertyRegistry {
     dummy("minecraft:int_range", DUMMY);
     dummy("minecraft:float_range", DUMMY);
     dummy("minecraft:time", DUMMY); // added in 1.14
-    dummy("minecraft:uuid", DUMMY);
+    dummy("minecraft:uuid", DUMMY); // added in 1.16
   }
 }