Strange Assert Error in product_card.dart

[FreekyFrank]

At run time my code is throwing an assert error in product_card.dart but as the attached jpg shows the value is negative.

I will happily send all of my code for the mdc_100_series but I thought I would ask if I could have done something stupid first.

To the best of my abilities everything is exactly as the 104#6 at the point of running the inactive menu! If I override the assertion another exception is thrown relating to aspect ratio so clearly something is wrong but I do not know where to look.

In the mean time I will rescan my code for stupid errors.