fix crc calculation

Author: pavel-kirienko

AGENTS.md

@@ -3,6 +3,10 @@
 Read `README.md` for general information about the library, and `CONTRIBUTING.md` for development-related notes.
 Read all README files in all subdirectories except for `lib/`.
 
+The applicable specifications can be found here:
+- **Cyphal v1**: https://github.com/OpenCyphal/specification
+- **UAVCAN v0**, aka DroneCAN: https://dronecan.github.io/Specification/4.1_CAN_bus_transport_layer
+
 Project layout:
 
 - `libcanard`: the library itself; the shippable code.

libcanard/canard.c

@@ -1366,8 +1366,8 @@ static void rx_session_accept(rx_session_t* const ses, const canard_us_t ts_fram
         // The CRC initial state is constant for v1, data-type-dependent for v0; this is managed outside of this scope.
         const canard_bytes_t crc_input =
           ((canard_kind_version(sub->kind) == 0) && fr->start)
-            ? fr->payload
-            : (canard_bytes_t){ .size = fr->payload.size - 2, .data = ((byte_t*)fr->payload.data) + 2 };
+            ? (canard_bytes_t){ .size = fr->payload.size - 2, .data = ((byte_t*)fr->payload.data) + 2 }
+            : fr->payload;
         slot->crc = crc_add(slot->crc, crc_input.size, crc_input.data);
     }
     if (fr->end) {