lnrpc: surface invalid onion blinding on rpc

lnrpc/routerrpc/router.swagger.json

@@ -577,6 +577,7 @@
         "EXPIRY_TOO_FAR",
         "MPP_TIMEOUT",
         "INVALID_ONION_PAYLOAD",
+        "INVALID_ONION_BLINDING",
         "INTERNAL_FAILURE",
         "UNKNOWN_FAILURE",
         "UNREADABLE_FAILURE"

lnrpc/routerrpc/router_backend.go

@@ -1495,6 +1495,10 @@ func marshallWireError(msg lnwire.FailureMessage,
 	case *lnwire.InvalidOnionPayload:
 		response.Code = lnrpc.Failure_INVALID_ONION_PAYLOAD
 
+	case *lnwire.FailInvalidBlinding:
+		response.Code = lnrpc.Failure_INVALID_ONION_BLINDING
+		response.OnionSha_256 = onionErr.OnionSHA256[:]
+
 	case nil:
 		response.Code = lnrpc.Failure_UNKNOWN_FAILURE