Fix ChargingBench (#4184)

Resolves #4183
* Fix ChargingBench
- ChargingBench can now only recharge ItemStacks with 1 item.

---------

Co-authored-by: J3fftw <44972470+J3fftw1@users.noreply.github.com>
Co-authored-by: JustAHuman-xD <65748158+JustAHuman-xD@users.noreply.github.com>

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/machines/ChargingBench.java

@@ -44,6 +44,10 @@ protected void tick(Block b) {
         for (int slot : getInputSlots()) {
             ItemStack item = inv.getItemInSlot(slot);
 
+            if (item == null || item.getAmount() != 1) {
+                continue;
+            }
+
             if (charge(b, inv, slot, item)) {
                 return;
             }