Fix appname resolution when outside Rails context (rails-sqlserver#943)

The adapter can be used outside a Rails context so TinyTDS appname config should
be able to be resolved if a Rails application was not detected.

Fix rails-sqlserver#942.

Author: wpolicarpo

CHANGELOG.md

@@ -1,3 +1,9 @@
+## Unreleased
+
+#### Fixed
+
+- [#943](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/943) Fix appname resolution when outside Rails context
+
 ## v6.1.2.0
 
 [Full changelog](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/compare/v6.1.1.0...v6.1.2.0)

lib/active_record/connection_adapters/sqlserver_adapter.rb

@@ -142,9 +142,9 @@ def config_appname(config)
         end
 
         def rails_application_name
-          return nil if Rails.application.nil?
-
           Rails.application.class.name.split("::").first
+        rescue
+          nil # Might not be in a Rails context so we fallback to `nil`.
         end
 
         def config_login_timeout(config)