error[E0599]: no method named `as_dyn_error` found for type `&std::string::String` in the current scope
 --> $DIR/source-enum-not-error.rs:7:9
  |
7 |         source: String,
  |         ^^^^^^ method not found in `&std::string::String`
  |
  = note: the method `as_dyn_error` exists but the following trait bounds were not satisfied:
          `&std::string::String : thiserror::aserror::AsDynError`
          `std::string::String : thiserror::aserror::AsDynError`
          `str : thiserror::aserror::AsDynError`