Fixed consume amount validation when consuming a parent product (fixes #1306)

More a workaround for now, the max constraint is just removed when the product has child products,
but the amount to be consumed is checked by StockService anyway, so should not be a problem...

public/viewjs/consume.js

@@ -127,6 +127,7 @@
 				},
 				function(xhr)
 				{
+					Grocy.FrontendHelpers.ShowGenericError('Error while saving, probably this item already exists', xhr.response);
 					Grocy.FrontendHelpers.EndUiBusy("consume-form");
 					console.error(xhr);
 				}
@@ -650,6 +651,11 @@ function RefreshForm()
 		}
 	}
 
+	if (productDetails.has_childs)
+	{
+		$("#display_amount").removeAttr("max");
+	}
+
 	Grocy.FrontendHelpers.ValidateForm("consume-form");
 }