flatpak: Check if error is null before trying to log a message
Apparently this callback can return a nullable error, but it's not listed in the docs.
As we can see in the backtrace, error is null (for whatever reason):
#4 0x00007fd9f81a65cb in operation_error_cb (error=0x0, user_data=0x558a93b29dd0) at /usr/src/debug/discover-5.27.7/libdiscover/backends/FlatpakBackend/FlatpakTransactionThread.cpp:65Not sure if this will fix the root cause for the poor NVIDIA update, but it should stop Discover from crashing at least. Should be backported to 5.27.