AspNetCore.Identity sample: cannot resolve IMongoClient

[morganreesoval]

We're running into an issue adding IdentityServer with Mongo stores + AspNetCore.Identity in our project. I cloned this repo and tried to run the AspNetIdentity.Sample, and a similar issue occurs, relating to failure to resolve IMongoClient. I notice the code to add IMongoClient exists in the IdentityServer.Sample but not the AspNetIdentity.Sample.

Does the call to add IMongoClient as a singleton need to be present when using AddIdentityMongoDbProvider? If so, in which order does it need to go when registering services, as we've also noticed having the calls in the wrong order causes exceptions to be thrown, crashing the app.