Build error during latest CI

[pattacini]

Hi @marcoaccame

Just spotted this build error during icub-main CI (see https://github.com/robotology/icub-main/actions/runs/1776034784):

[ 10%] Building CXX object embot/CMakeFiles/embot.dir/prot/eth/embot_prot_eth_diagnostic_Node.cpp.o
2022-02-01T02:35:42.3193101Z In file included from /home/runner/work/icub-main/icub-main/icub-firmware-shared/embot/prot/eth/embot_prot_eth_diagnostic_Node.h:17,
2022-02-01T02:35:42.3195229Z                  from /home/runner/work/icub-main/icub-main/icub-firmware-shared/embot/prot/eth/embot_prot_eth_diagnostic_Node.cpp:13:
2022-02-01T02:35:42.3197451Z /home/runner/work/icub-main/icub-main/icub-firmware-shared/embot/core/embot_core.h: In member function ‘bool embot::prot::eth::diagnostic::Node::Impl::init(const embot::prot::eth::diagnostic::Node::Config&)’:
2022-02-01T02:35:42.3200548Z /home/runner/work/icub-main/icub-main/icub-firmware-shared/embot/prot/eth/embot_prot_eth_diagnostic_Node.cpp:153:9:   in ‘constexpr’ expansion of ‘embot::core::Data(0, ((size_t)((uint16_t)embot::prot::eth::diagnostic::InfoBasic::sizeofobject)))’
2022-02-01T02:35:42.3201660Z /home/runner/work/icub-main/icub-main/icub-firmware-shared/embot/core/embot_core.h:130:59: error: conversion of ‘const void*’ null pointer to ‘void*’ is not a constant expression
2022-02-01T02:35:42.3202256Z   130 |         constexpr Data(const void *p, size_t s) : pointer(const_cast<void*>(p)), capacity(s) {}
2022-02-01T02:35:42.3202623Z       |                                                           ^~~~~~~~~~~~~~~~~~~~
2022-02-01T02:35:42.3203630Z /home/runner/work/icub-main/icub-main/icub-firmware-shared/embot/prot/eth/embot_prot_eth_diagnostic_Node.cpp:165:9:   in ‘constexpr’ expansion of ‘embot::core::Data(0, ((size_t)((uint16_t)embot::prot::eth::diagnostic::Info::sizeofobject)))’
2022-02-01T02:35:42.3204626Z /home/runner/work/icub-main/icub-main/icub-firmware-shared/embot/core/embot_core.h:130:59: error: conversion of ‘const void*’ null pointer to ‘void*’ is not a constant expression
2022-02-01T02:35:42.3249625Z /home/runner/work/icub-main/icub-main/icub-firmware-shared/embot/prot/eth/embot_prot_eth_diagnostic_Node.cpp:176:9:   in ‘constexpr’ expansion of ‘embot::core::Data(0, ((size_t)((uint16_t)embot::prot::eth::diagnostic::InfoLarge::sizeofobject)))’
2022-02-01T02:35:42.3250724Z /home/runner/work/icub-main/icub-main/icub-firmware-shared/embot/core/embot_core.h:130:59: error: conversion of ‘const void*’ null pointer to ‘void*’ is not a constant expression
2022-02-01T02:35:42.3594102Z make[2]: *** [embot/CMakeFiles/embot.dir/build.make:160: embot/CMakeFiles/embot.dir/prot/eth/embot_prot_eth_diagnostic_Node.cpp.o] Error 1
2022-02-01T02:35:42.3597373Z make[1]: *** [CMakeFiles/Makefile2:161: embot/CMakeFiles/embot.dir/all] Error 2
2022-02-01T02:35:42.3597789Z make: *** [Makefile:136: all] Error 2
2022-02-01T02:35:42.3622006Z ##[error]Process completed with exit code 2.

Could you please have a look at it?