sa-compile: command 're2c -i -b -o scanner1.c scanner1.re' failed: exit 0

While installing some software on my Debian 10.9 server, I received this error:

$ sudo apt-get install fail2ban

... [cut]

Running sa-compile (may take a long time)
command 're2c -i -b -o scanner1.c scanner1.re' failed: exit 0
dpkg: error processing package sa-compile (--configure):
 installed sa-compile package post-installation script subprocess returned error exit status 12
Setting up fail2ban (0.10.2-2.1)...

... [cut]

Errors were encountered while processing:
 sa-compile
E: Sub-process /usr/bin/dpkg returned an error code (1)

I have previously installed spamassassin (sa-compile's dependent). This confused me, so I tried to dpkg-reconfigure:

$ sudo dpkg-reconfigure sa-compile
/usr/sbin/dpkg-reconfigure: sa-compile is broken or not fully installed

Installing the package with --reinstall is a no-op. Using --fix-broken instead returns a familiar error:

$ sudo apt-get install --fix-broken sa-compile
Setting up sa-compile (3.4.2-1+deb10u3) ...
Running sa-compile (may take a long time)
command 're2c -i -b -o scanner1.c scanner1.re' failed: exit 0
dpkg: error processing package sa-compile (--configure):
 installed sa-compile package post-installation script subprocess returned error exit status 12
Errors were encountered while processing:
 sa-compile
E: Sub-process /usr/bin/dpkg returned an error code (1)

How do I go about fixing this?