For some reason it's trying to alter a file that doesn't exists /var/spool/amavisd/tmp/amavis-20230110T095247-31601-RpGveeFM/email-repl.txt, but /var/spool/amavisd/tmp/amavis-20230110T095247-31601-RpGveeFM/email.txt does exists
Are you sure that email-repl.txt did not exist? Amavis wants to create one in altermime context. Moreover, a missing altermime input yields
AM_add_disclaimer: Cannot open /path/to/file.txt, No such file or directory
but in your case it seems to have coredumped.
