impl transposed form of MapExpect

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/utils/result/map_expect.rs

@@ -13,3 +13,8 @@ impl<'a, T, E: Debug> MapExpect<'a, Option<T>> for Option<Result<T, E>> {
 	#[inline]
 	fn map_expect(self, msg: &'a str) -> Option<T> { self.map(|result| result.expect(msg)) }
 }
+
+impl<'a, T, E: Debug> MapExpect<'a, Result<T, E>> for Result<Option<T>, E> {
+	#[inline]
+	fn map_expect(self, msg: &'a str) -> Result<T, E> { self.map(|result| result.expect(msg)) }
+}