Added taxmode check to supplier invoice items

wiaflos/server/core/Purchasing.pm

@@ -751,6 +751,10 @@ sub linkSupplierInvoiceItem
 
 	# Get ready for calculating tax
 	my ($taxAmount,$taxMode) = wiaflos::server::core::Tax::getTaxAmount($detail->{'TaxMode'},$taxRate,$totalPrice);
+	if (!defined($taxMode)) {
+		setError(wiaflos::server::core::Tax::Error());
+		return $taxType;
+	}
 
 	# Calculate discount
 	if (!$discount->is_zero()) {