--- a/net/minecraft/network/chat/ChatSender.java
+++ b/net/minecraft/network/chat/ChatSender.java
@@ -8,6 +8,12 @@
 public record ChatSender(UUID profileId, @Nullable ProfilePublicKey profilePublicKey) {
     public static final ChatSender SYSTEM = new ChatSender(Util.NIL_UUID, (ProfilePublicKey)null);
 
+    // Paper start
+    public ChatSender {
+        com.google.common.base.Preconditions.checkNotNull(profileId, "uuid cannot be null");
+    }
+    // Paper end
+
     public boolean isSystem() {
         return SYSTEM.equals(this);
     }
