Use thiserror for UserNotFoundError.

client/src/user/map.rs

@@ -1,27 +1,13 @@
 use std::collections;
-use std::error;
-use std::fmt;
+
+use thiserror::Error;
 
 use solstice_proto::{User, UserStatus};
 
 /// The error returned when a user name was not found in the user map.
-#[derive(Debug)]
-pub struct UserNotFoundError {
-  /// The name of the user that wasn't found.
-  user_name: String,
-}
-
-impl fmt::Display for UserNotFoundError {
-  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-    write!(f, "user \"{}\" not found", self.user_name)
-  }
-}
-
-impl error::Error for UserNotFoundError {
-  fn description(&self) -> &str {
-    "user not found"
-  }
-}
+#[derive(Debug, Error)]
+#[error("user {0:?} not found")]
+pub struct UserNotFoundError(String);
 
 /// Contains the mapping from user names to user data and provides a clean
 /// interface to interact with it.
@@ -54,9 +40,7 @@ impl UserMap {
   ) -> Result<&mut User, UserNotFoundError> {
     match self.map.get_mut(user_name) {
       Some(user) => Ok(user),
-      None => Err(UserNotFoundError {
-        user_name: user_name.to_string(),
-      }),
+      None => Err(UserNotFoundError(user_name.to_string())),
     }
   }