E1.31: fix crash on wrong packet format
E1.31: fix crash on wrong packet format

a crash occurs when the length written in the packet it too big

plugz/qlcplus,plugz/qlcplus,sbenejam/qlcplus,plugz/qlcplus,kripton/qlcplus,mcallegari/qlcplus,kripton/qlcplus,kripton/qlcplus,kripton/qlcplus,sbenejam/qlcplus,mcallegari/qlcplus,mcallegari/qlcplus,mcallegari/qlcplus,sbenejam/qlcplus,kripton/qlcplus,sbenejam/qlcplus,plugz/qlcplus,mcallegari/qlcplus,sbenejam/qlcplus,sbenejam/qlcplus,plugz/qlcplus,mcallegari/qlcplus,kripton/qlcplus,sbenejam/qlcplus,mcallegari/qlcplus,plugz/qlcplus,kripton/qlcplus,plugz/qlcplus