Fortmatic: the app does not show an error when cancel a transition signing request

[anxolin]

Originally reported in https://github.com/gnosis/cowswap/pull/2388#issuecomment-1030129467

Steps: connect to the Fortmatic wallet Start any sell/buy order transaction Cancel (close) signing Fortmatic wallet

AR: the Cowswap app still shows 'pending' signing modal https://watch.screencastify.com/v/4oUhXdp7lBovwyTTYTsq

ER: the app should show an error message

Original issue https://github.com/gnosis/cowswap/issues/2413 by @elena-zh

[elena-zh]

Closed as the Fortmatic wallet is going to be removed from the app