Fix the packet sending procedure.

ProtocolLib/src/main/java/com/comphenix/protocol/async/PacketSendingQueue.java

@@ -174,10 +174,17 @@ abstract class PacketSendingQueue {
 				// Recompute
 				marker = current.getAsyncMarker();
 				hasExpired = marker.hasExpired();
+				
+				// Could happen due to the timeout listeners
+				if (!marker.isProcessed()) {
+					return false;
+				}
 			}
 			
-			// Abort if we're not on the main thread
+			// Is it okay to send the packet?
-			if (notThreadSafe && !hasExpired) {
+			if (!current.isCancelled() && !hasExpired) {
+				// Make sure we're on the main thread
+				if (notThreadSafe) {
 					try {
 						boolean wantAsync = marker.isMinecraftAsync(current);
 						boolean wantSync = !wantAsync;
@@ -187,7 +194,7 @@ abstract class PacketSendingQueue {
 							return false;
 						}
 						
-					// Let's give it what it wants, then
+						// Let's give it what it wants
 						if (onMainThread && wantAsync) {
 							asynchronousSender.execute(new Runnable() {
 								@Override
@@ -197,31 +204,31 @@ abstract class PacketSendingQueue {
 								}
 							});
 							
-						// The executor will take it from here
+							// Scheduler will do the rest
 							return true;
 						}
 						
 					} catch (FieldAccessException e) {
 						e.printStackTrace();
-					// Skip this packet
+						
+						// Just drop the packet
 						return true;
 					}
 				} 
 				
-			if (marker.isProcessed() && !current.isCancelled() && !hasExpired) {
 				// Silently skip players that have logged out
 				if (isOnline(current.getPlayer())) {
 					sendPacket(current);
 				}
 			} 
 			
+			// Drop the packet
 			return true;
+		}
 		
-		} else {
 		// Add it back and stop sending
 		return false;
 	}
-	}
 	
 	/**
 	 * Invoked when a packet has timed out.