elliptic-curve: der error handling fixups (#1912)

Companion PR to RustCrypto/formats#1889

Author: tarcieri

Cargo.lock

@@ -16,3 +16,7 @@ members = [
 [patch.crates-io]
 digest = { path = "digest" }
 signature = { path = "signature" }
+
+der = { git = "https://github.com/RustCrypto/formats.git" }
+pkcs8 = { git = "https://github.com/RustCrypto/formats.git" }
+sec1 = { git = "https://github.com/RustCrypto/formats.git" }

Cargo.toml

@@ -467,10 +467,10 @@ where
         let public_key_bytes = spki
             .subject_public_key
             .as_bytes()
-            .ok_or_else(|| der::Tag::BitString.value_error())?;
+            .ok_or_else(|| der::Tag::BitString.value_error().to_error())?;
 
         Self::from_sec1_bytes(public_key_bytes)
-            .map_err(|_| der::Tag::BitString.value_error().into())
+            .map_err(|_| der::Tag::BitString.value_error().to_error().into())
     }
 }
 

elliptic-curve/src/public_key.rs

@@ -374,7 +374,7 @@ where
     fn try_from(sec1_private_key: sec1::EcPrivateKey<'_>) -> der::Result<Self> {
         if let Some(sec1::EcParameters::NamedCurve(curve_oid)) = sec1_private_key.parameters {
             if C::OID != curve_oid {
-                return Err(der::Tag::ObjectIdentifier.value_error());
+                return Err(der::Tag::ObjectIdentifier.value_error().into());
             }
         }
 
@@ -386,7 +386,7 @@ where
                 .map_err(|_| der::Tag::BitString.value_error())?;
 
             if C::validate_public_key(&secret_key, &pk).is_err() {
-                return Err(der::Tag::BitString.value_error());
+                return Err(der::Tag::BitString.value_error().into());
             }
         }