Suppress failures to add user secrets

[natemcmaster]

Two things can go wrong:

1. Assembly.Load failures if env.ApplicationName does not correspond to a valid assembly
2. No UserSecretsIdAttribute on the assembly

Resolves #60

[davidfowl]

Assembly.Load failures if env.ApplicationName does not correspond to a valid assembly

Super rare. Just let it explode. Other parts of the stack try to Load(env.ApplicationName) already so don't bother.

No UserSecretsIdAttribute on the assembly

I'd rather add detection using reflection than by catching exceptions. No first chance exceptions in ASP.NET Core! 😄

[natemcmaster]

How about instead we add an optional setting to the .AddUserSecrets call?

[davidfowl]

How about instead we add an optional setting to the .AddUserSecrets call?

That was my first choice. Make it like the other providers.

[DamianEdwards]

A bool to suppress errors?

[natemcmaster]

I was thinking of adding .AddUserSecrets(Assembly assembly, bool optional) and .AddUserSecrets<T>(bool optional)

[DamianEdwards]

Yup

[natemcmaster]

K, let's to that. See aspnet/Configuration#654.

I'll open a PR to use the optional = true setting when it's it.