Fix DroneCAN/UAVCANv0 handling of uavcan.protocol.file.Read responses (…

…#28)

An empty response to the uavcan.protocol.file.Read will have a size of 2 bytes (this is the size of the error field), while the DroneCAN -> Cyphal converter expects at least 4, because it mistakenly assumes that the minimum response size will be like in Cyphal, where there is no tail array optimization.

kocherga/kocherga_can.hpp

@@ -1250,7 +1250,7 @@ class V0MainActivity : public IActivity
                                         const std::size_t         response_size,
                                         const std::uint8_t* const response_data)
     {
-        if (response_size >= 4)
+        if (response_size >= 2)
         {
             std::array<std::uint8_t, 270> buf{};
             buf.back()     = 0xAA;