simplify hash lock signature check

cashu/mint/conditions.py

@@ -175,20 +175,20 @@ def _verify_input_spending_conditions(self, proof: Proof) -> bool:
 
             # then we check whether a signature is required
             hashlock_pubkeys = htlc_secret.tags.get_tag_all("pubkeys")
-            if hashlock_pubkeys and not proof.htlcsignature:
-                # none of the pubkeys had a match
-                raise TransactionError("HTLC no hash lock signatures provided.")
-            for pubkey in hashlock_pubkeys:
-                if verify_p2pk_signature(
-                    message=htlc_secret.serialize().encode("utf-8"),
-                    pubkey=PublicKey(bytes.fromhex(pubkey), raw=True),
-                    signature=bytes.fromhex(proof.htlcsignature),
-                ):
-                    # a signature matches
-                    return True
             if hashlock_pubkeys:
-                # none of the pubkeys had a match
-                raise TransactionError("HTLC hash lock signatures did not match.")
+                assert proof.htlcsignature, TransactionError(
+                    "HTLC no hash lock signatures provided."
+                )
+                for pubkey in hashlock_pubkeys:
+                    if verify_p2pk_signature(
+                        message=htlc_secret.serialize().encode("utf-8"),
+                        pubkey=PublicKey(bytes.fromhex(pubkey), raw=True),
+                        signature=bytes.fromhex(proof.htlcsignature),
+                    ):
+                        # a signature matches
+                        return True
+                    # none of the pubkeys had a match
+                    raise TransactionError("HTLC hash lock signatures did not match.")
             # no pubkeys were included, anyone can spend
             return True