Implement std::Error for HWI's errors

Author: danielabrozzoni

src/error.rs

@@ -1,3 +1,5 @@
+use std::fmt;
+
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub enum Error {
     JSON(String),
@@ -22,3 +24,11 @@ impl_error!(serde_json::Error, JSON);
 impl_error!(std::str::Utf8Error, Utf8);
 impl_error!(std::io::Error, IOError);
 impl_error!(pyo3::prelude::PyErr, PyErr);
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
+impl std::error::Error for Error {}