🚀 go-pugleaf

The following input (modulo the leading XX) on Ultrix 2.2 nroff and troff
(with -me) generates a "Bad storage error" when trying to process the .  I'm
trying to do multiple indices (and even get them sorted!), without much
success.  Any suggestions as to what is going wrong here.  (I know that 'pi'
was a bad choice for a macro name, as it's already used, but why the
internal error?  Other hints, suggestions, and comments welcome.  Thanks.

XX.fo 'PAGE BOTTOM'%'PAGE BOTTOM'
XX.de pi
XX.(x p
XX\\$1
XX.)x \n%
XX..
XX.de ti
XX.(x t
XX\\$1
XX.)x \n%
XX..
XX.de vi
XX.(x v
XX\\$1
XX.)x \n%
XX..
XX.de oi
XX.(x o
XX\\$1
XX.)x \n%
XX..
XX.bp
XXSmith
XX.pi "Smith, James"
XX.oi "Smith, James"
XX.ti "Smith, James"
XX.vi "Smith, James"
XX.bp
XXJohnson
XX.pi "Johnson, James"
XX.oi "Johnson, James"
XX.ti "Johnson, James"
XX.vi "Johnson, James"
XX.bp
XXJones
XX.pi "Jones, James"
XX.oi "Jones, James"
XX.ti "Jones, James"
XX.vi "Jones, James"
XX.bp
XXP Index
XX.xp p
XX.bp
XXT Index
XX.xp t
XX.bp
XXV Index
XX.xp v
XX.bp
XXO Index
XX.xp o