do not access elements of empty vector #138

Job	Run time
coverage - measure	1m 37s
ios	2m 52s
android	4m 7s
conan - linux - x86_64	1m 51s
linux - debian:bookworm \|	1m 48s
macosx	3m 41s
linux - debian:bookworm \| arm32	11m 7s
msvs	2m 58s
msys2 - mingw32	3m 35s
linux - debian:bookworm \| arm64	2m 52s
msys2 - mingw64	2m 23s
linux - ubuntu:jammy \|	1m 42s
sanitizer - debian:bookworm \|	1m 42s
linux - ubuntu:noble \|	1m 49s
sanitizer - debian:bookworm \| arm32	10m 40s
linux - igagis/raspbian:bookworm \| arm32	7m 48s
sanitizer - debian:bookworm \| arm64	2m 36s
	1h 5m 8s

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