Add String value to the Error::UnexpectedError variant

To make debugging of unexpected errors easier, this patch adds an
associated String value with a description of the unexpected behavior to
the UnexpectedError variant of the Error enum.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/error.rs b/src/error.rs
index f9af594..7bea3f2 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -25,7 +25,7 @@ pub enum Error {
     /// An error that occurred during random number generation.
     RandError(Box<dyn error::Error>),
     /// An error that is caused by an unexpected value returned by libnitrokey.
-    UnexpectedError,
+    UnexpectedError(String),
     /// An unknown error returned by libnitrokey.
     UnknownError(i64),
     /// An error caused by a Nitrokey model that is not supported by this crate.
@@ -102,7 +102,7 @@ impl error::Error for Error {
             Error::LibraryError(ref err) => Some(err),
             Error::PoisonError(ref err) => Some(err),
             Error::RandError(ref err) => Some(err.as_ref()),
-            Error::UnexpectedError => None,
+            Error::UnexpectedError(_) => None,
             Error::UnknownError(_) => None,
             Error::UnsupportedModelError => None,
             Error::Utf8Error(ref err) => Some(err),
@@ -119,7 +119,7 @@ impl fmt::Display for Error {
             Error::LibraryError(ref err) => write!(f, "Library error: {}", err),
             Error::PoisonError(_) => write!(f, "Internal error: poisoned lock"),
             Error::RandError(ref err) => write!(f, "RNG error: {}", err),
-            Error::UnexpectedError => write!(f, "An unexpected error occurred"),
+            Error::UnexpectedError(ref s) => write!(f, "An unexpected error occurred: {}", s),
             Error::UnknownError(ref err) => write!(f, "Unknown error: {}", err),
             Error::UnsupportedModelError => write!(f, "Unsupported Nitrokey model"),
             Error::Utf8Error(ref err) => write!(f, "UTF-8 error: {}", err),