ipfixprobe segfaults when there are more output plugin groups than output files

[PaulosV]

I have accidentally triggered a segfault while trying to convert a PCAP file to UniRec format. This was the command:

$ ipfixprobe -i 'pcap;file=./test1/2023-08-24-out_wan.pcap' -p pstats -p phists -o "unirec;i=f:test1.trapcap:w;p=pstats,phists"
ERROR: trap_ctx_vset_data_fmt: Uninitialized libtrap context or bad parameters.
Segmentation fault (core dumped)

There are two output plugin groups - pstats, phists - but only one output file - test1.trapcap.