Handle the possibility that getSuperclass() returns NULL.

Thanks to libraryaddict for discovering this bug.

ProtocolLib/src/main/java/com/comphenix/protocol/CommandPacket.java

@@ -339,8 +339,9 @@ class CommandPacket extends CommandBase {
 						Class<?> clazz = packet.getClass();
 						
 						// Get the first Minecraft super class
-						while ((!MinecraftReflection.isMinecraftClass(clazz) || 
-								 Factory.class.isAssignableFrom(clazz)) && clazz != Object.class) {
+						while (clazz != null && clazz != Object.class &&
+								(!MinecraftReflection.isMinecraftClass(clazz) || 
+								 Factory.class.isAssignableFrom(clazz))) {
 							clazz = clazz.getSuperclass();
 						}
 						

ProtocolLib/src/main/java/com/comphenix/protocol/reflect/ObjectWriter.java

@@ -119,7 +119,7 @@ public class ObjectWriter {
 			// Copy private fields underneath
 			Class<?> superclass = commonType.getSuperclass();
 			
-			if (!superclass.equals(Object.class)) {
+			if (superclass != null && !superclass.equals(Object.class)) {
 				copyToInternal(source, destination, superclass, false);
 			}
 			

ProtocolLib/src/main/java/com/comphenix/protocol/reflect/PrettyPrinter.java

@@ -210,7 +210,7 @@ public class PrettyPrinter {
 									ObjectPrinter printer) throws IllegalAccessException {
 		
 		// See if we're supposed to skip this class
-		if (current == Object.class || (stop != null && current.equals(stop))) {
+		if (current == null || current == Object.class || (stop != null && current.equals(stop))) {
 			return;
 		}