lexgrog confused by `IR` call in (singleton) topic list

Exhibit:

$ cat /tmp/proc_pid_fdinfo_summary.5
.TH proc_pid_fdinfo_mini 5 2024-11-02 "example"
.SH Name
.IR /proc/ pid /fdinfo " \- information about file descriptors"
.SH Description
Text text text text.
$ lexgrog /tmp/proc_pid_fdinfo_summary.5
/tmp/proc_pid_fdinfo_summary.5: parse failed
$ nroff -v | head -n 1
GNU nroff (groff) version 1.23.0
$ nroff -ww -rCHECKSTYLE=4 -man /tmp/proc_pid_fdinfo_summary.5 
proc_pid_fdinfo_mini(5)       File Formats Manual      proc_pid_fdinfo_mini(5)

Name
       /proc/pid/fdinfo - information about file descriptors

Description
       Text text text text.

example                           2024‐11‐02           proc_pid_fdinfo_mini(5)