chore: fix failing test

Author: thisisabhash

AmplifyPlugins/Auth/Sources/AWSCognitoAuthPlugin/Models/AWSAuthCognitoSession.swift

@@ -64,8 +64,13 @@ public struct AWSAuthCognitoSession: AuthSession,
             return .failure(AuthError.signedOut(
                             AuthPluginErrorConstants.userSubSignOutError.errorDescription,
                             AuthPluginErrorConstants.userSubSignOutError.recoverySuggestion))
+        } catch let error as AuthError {
+            return .failure(error)
         } catch {
-            return .failure(error as AuthError)
+            let error = AuthError.unknown("""
+                            Could not retreive user sub from the fetched Cognito tokens.
+                            """)
+            return .failure(error)
         }
     }