Quantity check for locked products

[serpico]

Not sure exactly where the root cause is, could be carelessness of user/script tasked to input quantity values for locked/protected products, here are several examples :

3256224632047
3256221106831
3256221654004
3256222649283
3256222234465
3256222114170

As a result open-prices display wrong values which would also mess up the price per kilo calculations.
Sometimes comparing quantity and serving_quantity helps but not always.
Due to the protected status a normal user wouldn't be able to correct those value on OFF, although I didn't try to activate DEV mode on smoothie to see if the value are still uneditable .