Remove use of unwrap (#1888)

* Remove use of unwrap

* Update changelog

* Update CHANGELOG.md

Co-authored-by: Mo Mirza <mo.mirza@iwoca.co.uk>
Co-authored-by: David Hewitt <1939362+davidhewitt@users.noreply.github.com>

CHANGELOG.md

@@ -41,6 +41,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix building with a conda environment on Windows. [#1873](https://github.com/PyO3/pyo3/pull/1873)
 - Fix panic on Python 3.6 when calling `Python::with_gil` with Python initialized but threading not initialized. [#1874](https://github.com/PyO3/pyo3/pull/1874)
 - Fix incorrect linking to version-specific DLL instead of `python3.dll` when cross-compiling to Windows with `abi3`. [#1880](https://github.com/PyO3/pyo3/pull/1880)
+- Fix panic in generated `#[derive(FromPyObject)]` for enums. [#1888](https://github.com/PyO3/pyo3/pull/1888)
 
 ## [0.14.5] - 2021-09-05
 

pyo3-macros-backend/src/from_pyobject.rs

@@ -63,7 +63,7 @@ impl<'a> Enum<'a> {
                     ok @ ::std::result::Result::Ok(_) => return ok,
                     ::std::result::Result::Err(inner) => {
                         let py = ::pyo3::PyNativeType::py(obj);
-                        err_reasons.push_str(&::std::format!("{}\n", inner.instance(py).str().unwrap()));
+                        err_reasons.push_str(&::std::format!("{}\n", inner.instance(py).str()?));
                     }
                 }
             );