I have also tried the package from https://pkgsrc.zia.io/pub/pkgsrc/packages/NetBSD/sparc64/9.0_2022Q4/All/ with the same crash result. After that i have bootstrapped pkgsrc-2020Q4 into a different directory and built the complete dependency chain to build firefox52-52.9.0nb32.tgz This firefox52 works and tells me that the base system of NetBSD 9.3 is not the root cause.
The bulk packages are built using a standard chroot of just NetBSD 9.0. That it works when built in 9.3 but not in 9.0 may be a clue.
gcc switched from 7.4.0 to 7.5.0 after 9.0. Perhaps this is a factor?I'm going to make a new, clean, NetBSD 9.3 chroot and start a clean build of firefox52 without any old dependencies to gather more details.
Thanks, John Klos