Fix IllegalArgumentException with watchable objects

ProtocolLib/src/main/java/com/comphenix/protocol/utility/MinecraftReflection.java

@@ -424,7 +424,8 @@ public class MinecraftReflection {
 	 * @return TRUE if it can, FALSE otherwise.
 	 */
 	public static boolean isBlockPosition(Object obj) {
-		return obj != null && getBlockPositionClass().isAssignableFrom(obj.getClass());
+		Class<?> blockPosition = getBlockPositionClass();
+		return obj != null && blockPosition != null && blockPosition.isAssignableFrom(obj.getClass());
 	}
 
 	/**
@@ -1179,7 +1180,8 @@ public class MinecraftReflection {
 		try {
 			return getMinecraftClass("ChunkPosition");
 		} catch (RuntimeException e) {
-			/* Class<?> normalChunkGenerator = getCraftBukkitClass("generator.NormalChunkGenerator");
+			try {
+				Class<?> normalChunkGenerator = getCraftBukkitClass("generator.NormalChunkGenerator");
 
 				// ChunkPosition a(net.minecraft.server.World world, String string, int i, int i1, int i2) {
 				FuzzyMethodContract selected = FuzzyMethodContract.newBuilder()
@@ -1191,19 +1193,24 @@ public class MinecraftReflection {
 						.parameterExactType(int.class, 4)
 						.build();
 
-			return setMinecraftClass("ChunkPosition", FuzzyReflection.fromClass(normalChunkGenerator).getMethod(selected).getReturnType()); */
+				return setMinecraftClass("ChunkPosition",
+						FuzzyReflection.fromClass(normalChunkGenerator).getMethod(selected).getReturnType());
+			} catch (Throwable ex) {
 				return null;
 			}
 		}
+	}
 
 	/**
 	 * Retrieves the BlockPosition class.
+	 * 
 	 * @return The BlockPosition class.
 	 */
 	public static Class<?> getBlockPositionClass() {
 		try {
 			return getMinecraftClass("BlockPosition");
 		} catch (RuntimeException e) {
+			try {
 				Class<?> normalChunkGenerator = getCraftBukkitClass("generator.NormalChunkGenerator");
 
 				// BlockPosition findNearestMapFeature(World, String, BlockPosition)
@@ -1216,6 +1223,9 @@ public class MinecraftReflection {
 
 				return setMinecraftClass("BlockPosition",
 						FuzzyReflection.fromClass(normalChunkGenerator).getMethod(selected).getReturnType());
+			} catch (Throwable ex) {
+				return null;
+			}
 		}
 	}