Add error modal if the purchase fails.
Add error modal if the purchase fails.

jjeffryes/openbazaar-desktop,jashot7/openbazaar-desktop,OpenBazaar/openbazaar-desktop,jjeffryes/openbazaar-desktop,jashot7/openbazaar-desktop,jjeffryes/openbazaar-desktop,OpenBazaar/openbazaar-desktop,jashot7/openbazaar-desktop,OpenBazaar/openbazaar-desktop