Program: 30804
Project: 30804
Buggy source:
@Override public boolean isItemValid(ItemStack i){
  if (i == null)   return false;
  if (i.getItem() == null)   return false;
  if (!inventory.isItemValidForSlot(this.getSlotIndex(),i) && !(inventory instanceof UpgradeInventory))   return false;
  IAppEngApi api=AEApi.instance();
switch (which) {
case VALID_ENCODED_PATTERN_W_OUPUT:
case ENCODED_PATTERN_W_OUTPUT:
case ENCODED_PATTERN:
{
      ICraftingPatternMAC pattern=i.getItem() instanceof ICraftingPatternItem ? ((ICraftingPatternItem)i.getItem()).getPatternForItem(i) : null;
      if (pattern != null)       return pattern.isEncoded();
      return false;
    }
case BLANK_PATTERN:
{
    ICraftingPatternMAC pattern=i.getItem() instanceof ICraftingPatternItem ? ((ICraftingPatternItem)i.getItem()).getPatternForItem(i) : null;
    if (pattern != null)     return !pattern.isEncoded();
    return false;
  }
case ORE:
return appeng.api.AEApi.instance().registries().grinder().getRecipeForInput(i) != null;
case FUEL:
return TileEntityFurnace.getItemBurnTime(i) > 0;
case POWERED_TOOL:
return Platform.isChargeable(i);
case QE_SINGULARTIY:
return api.materials().materialQESingularity.sameAs(i);
case RANGE_BOOSTER:
return api.materials().materialWirelessBooster.sameAs(i);
case SPATIAL_STORAGE_CELLS:
return i.getItem() instanceof ISpatialStorageCell && ((ISpatialStorageCell)i.getItem()).isSpatialStorage(i);
case STORAGE_CELLS:
return AEApi.instance().registries().cell().isCellHandled(i);
case WORKBENCH_CELL:
return i != null && i.getItem() instanceof ICellWorkbenchItem && ((ICellWorkbenchItem)i.getItem()).isEditable(i);
case STORAGE_COMPONENT:
boolean isComp=i.getItem() instanceof IStorageComponent && ((IStorageComponent)i.getItem()).isStorageComponent(i);
return isComp;
case TRASH:
if (AEApi.instance().registries().cell().isCellHandled(i)) return false;
if (i.getItem() instanceof IStorageComponent && ((IStorageComponent)i.getItem()).isStorageComponent(i)) return false;
return true;
case WIRELESS_TERMINAL:
return AEApi.instance().registries().wireless().isWirelessTerminal(i);
case BIOMETRIC_CARD:
return i.getItem() instanceof IBiometricCard;
case UPGRADES:
return i.getItem() instanceof IUpgradeModule && ((IUpgradeModule)i.getItem()).getType(i) != null;
default :
break;
}
return false;
}

Fixed version (ground truth):
@Override public boolean isItemValid(ItemStack i){
  if (i == null)   return false;
  if (i.getItem() == null)   return false;
  if (!inventory.isItemValidForSlot(this.getSlotIndex(),i))   return false;
  IAppEngApi api=AEApi.instance();
switch (which) {
case VALID_ENCODED_PATTERN_W_OUPUT:
case ENCODED_PATTERN_W_OUTPUT:
case ENCODED_PATTERN:
{
      ICraftingPatternMAC pattern=i.getItem() instanceof ICraftingPatternItem ? ((ICraftingPatternItem)i.getItem()).getPatternForItem(i) : null;
      if (pattern != null)       return pattern.isEncoded();
      return false;
    }
case BLANK_PATTERN:
{
    ICraftingPatternMAC pattern=i.getItem() instanceof ICraftingPatternItem ? ((ICraftingPatternItem)i.getItem()).getPatternForItem(i) : null;
    if (pattern != null)     return !pattern.isEncoded();
    return false;
  }
case ORE:
return appeng.api.AEApi.instance().registries().grinder().getRecipeForInput(i) != null;
case FUEL:
return TileEntityFurnace.getItemBurnTime(i) > 0;
case POWERED_TOOL:
return Platform.isChargeable(i);
case QE_SINGULARTIY:
return api.materials().materialQESingularity.sameAs(i);
case RANGE_BOOSTER:
return api.materials().materialWirelessBooster.sameAs(i);
case SPATIAL_STORAGE_CELLS:
return i.getItem() instanceof ISpatialStorageCell && ((ISpatialStorageCell)i.getItem()).isSpatialStorage(i);
case STORAGE_CELLS:
return AEApi.instance().registries().cell().isCellHandled(i);
case WORKBENCH_CELL:
return i != null && i.getItem() instanceof ICellWorkbenchItem && ((ICellWorkbenchItem)i.getItem()).isEditable(i);
case STORAGE_COMPONENT:
boolean isComp=i.getItem() instanceof IStorageComponent && ((IStorageComponent)i.getItem()).isStorageComponent(i);
return isComp;
case TRASH:
if (AEApi.instance().registries().cell().isCellHandled(i)) return false;
if (i.getItem() instanceof IStorageComponent && ((IStorageComponent)i.getItem()).isStorageComponent(i)) return false;
return true;
case WIRELESS_TERMINAL:
return AEApi.instance().registries().wireless().isWirelessTerminal(i);
case BIOMETRIC_CARD:
return i.getItem() instanceof IBiometricCard;
case UPGRADES:
return i.getItem() instanceof IUpgradeModule && ((IUpgradeModule)i.getItem()).getType(i) != null;
default :
break;
}
return false;
}