Error with SIGCHLD trap and process substitution

[Tavian Barnes]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -march=x86-64 -mtune=generic -O2 -pipe -fno-plt
-fexceptions         -Wp,-D_FORTIFY_SOURCE=2 -Wfo
rmat -Werror=format-security         -fstack-clash-protection
-fcf-protection -g -ffile-prefix-map=/build/bash/src=/u
sr/src/debug/bash -flto=auto
-DDEFAULT_PATH_VALUE='/usr/local/sbin:/usr/local/bin:/usr/bin'
-DSTANDARD_UTILS_PATH='/u
sr/bin' -DSYS_BASHRC='/etc/bash.bashrc'
-DSYS_BASH_LOGOUT='/etc/bash.bash_logout'
-DNON_INTERACTIVE_LOGIN_SHELLS
uname output: Linux tachyon 6.7.2-arch1-2 #1 SMP PREEMPT_DYNAMIC Wed,
31 Jan 2024 09:22:15 +0000 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.2
Patch Level: 26
Release Status: release

Description:

When a SIGCHLD trap is set, commands that include two process
substitutions fail with a strange "unexpected EOF" error.

Repeat-By:

[tavianator@tachyon ~]$ trap : SIGCHLD
[tavianator@tachyon ~]$ echo "$(id -u):$(id -g)"
bash: trap: line 2: unexpected EOF while looking for matching `)'
bash: command substitution: line 4: syntax error near unexpected token `)'
bash: command substitution: line 4: `id -g)'