Actually fix #500, mode changed to VarIntEnum at 1.8->1.9 but we never changed it.

src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/packets/InventoryPackets.java

@@ -248,7 +248,7 @@ public class InventoryPackets {
                 map(Type.SHORT); // 1 - Slot ID
                 map(Type.BYTE); // 2 - Button
                 map(Type.SHORT); // 3 - Action
-                map(Type.BYTE); // 4 - Mode
+                map(Type.VAR_INT, Type.BYTE); // 4 - Mode
                 map(Type.ITEM); // 5 - Clicked Item
                 handler(new PacketHandler() {
                     @Override

src/main/java/us/myles/ViaVersion/protocols/protocolsnapshotto1_10/packets/InventoryPackets.java

@@ -112,7 +112,7 @@ public class InventoryPackets {
                         map(Type.SHORT); // 1 - Slot
                         map(Type.BYTE); // 2 - Button
                         map(Type.SHORT); // 3 - Action number
-                        map(Type.BYTE); // 4 - Mode
+                        map(Type.VAR_INT); // 4 - Mode
                         map(Type.ITEM); // 5 - Clicked Item
 
                         handler(new PacketHandler() {