repair subscription function
repair subscription function

Previously, a subscriber would be added to the consnesus subscription
database even if an error was returned during the subscription process.

Now, the subscriber will only be added to the subscription database if
there are no errors.

Mingling94/Sia,mtlynch/Sia,MrStrong/Sia,johnathanhowell/Sia,mharkus/Sia,rivine/rivine,ChrisSchinnerl/Sia,MrStrong/Sia,mtlynch/Sia,ChrisSchinnerl/Sia,mnsl/Sia,ericflo/Sia,mharkus/Sia,rivine/rivine,NebulousLabs/Sia,ericflo/Sia,NebulousLabs/Sia,mnsl/Sia