Stop duplication in error source chain

Don't both print the contained error in the Display impl and also return
it in source

Author: faern

mullvad-encrypted-dns-proxy/src/config_resolver.rs

@@ -34,8 +34,8 @@ impl fmt::Display for Error {
 impl std::error::Error for Error {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
         match self {
-            Self::ResolutionError(ref err) => Some(err),
-            Self::Timeout(ref err) => Some(err),
+            Self::ResolutionError(ref err) => err.source(),
+            Self::Timeout(ref err) => err.source(),
         }
     }
 }