[NTG-context] lmt_followtext crashes while standard followtext itself works

The following example has been extracted from my automatically generated MP code. \starttext \startMPpage string texstring; texstring := "{\colored [r=0.00, g=0.00, b=0.00]{\definebodyfont [9.0pt][rm][default=Regular at 9.0pt]\switchtobodyfont [9.0pt]\setupinterlinespace [9.9pt]\tf E.g. publish/ subscribe}}"; path parpath; parpath := (238,-167.00010681152344)..controls (238,-167.00010681152344) and (238,-167.00010681152344) ..(238,-167.00010681152344)..controls (238,-166.60010673470143) and (238,-166.20010665787942) ..(238,-165.80010658105741)..controls (238,-165.40010643392299) and (238,-165.00010628678857) ..(238,-164.60010613965414)..controls (238,-164.2001060472048) and (238,-163.80010595475545) ..(238,-163.40010586230611)..controls (238,-155.56353466513065) and (231.9683162849897,-149) ..(224.2552179837387,-149)..controls (223.85521783436539,-149) and (223.45521768499208,-149) ..(223.05521753561877,-149)..controls (222.65521740514737,-149) and (222.255217274676,-149) ..(221.8552171442046,-149)..controls (221.45521705001735,-149) and (221.0552169558301,-149) ..(220.65521686164286,-149)..controls (220.25521665589685,-149) and (219.85521645015083,-149) ..(219.45521624440482,-149)..controls (219.05521631807508,-149) and (218.65521639174534,-149) ..(218.2552164654156,-149)..controls (217.85521724037432,-149) and (217.45521801533303,-149) ..(217.05521879029175,-149)..controls (216.6552203077878,-149) and (216.25522182528385,-149) ..(215.85522334277991,-149)..controls (215.45522405083273,-149) and (215.05522475888554,-149) ..(214.65522546693836,-149)..controls (214.25522550518758,-149) and (213.8552255434368,-149) ..(213.45522558168602,-149)..controls (213.0552253720042,-149) and (212.65522516232238,-149) ..(212.25522495264056,-149)..controls (211.8552248680295,-149) and (211.45522478341843,-149) ..(211.05522469880736,-149)..controls (210.65522456100436,-149) and (210.25522442320135,-149) ..(209.85522428539835,-149)..controls (209.45522414149036,-149) and (209.05522399758237,-149) ..(208.65522385367439,-149)..controls (200.95716230583835,-149) and (195,-155.63452868682958) ..(195,-163.48966401016395)..controls (195,-163.88966411101083) and (195,-164.28966421185771) ..(195,-164.68966431270459)..controls (195,-165.08966445890775) and (195,-165.4896646051109) ..(195,-165.88966475131406)..controls (195,-166.25981210471718) and (195,-166.62995945812031) ..(195,-167.00010681152344); picture pic; pic := lmt_followtext [ text = texstring, path = parpath, spread = false, ]; \stopMPpage \stoptext lmt_followtext crashes on this code with: metapost log > ! angle(0,0) is taken as zero. metapost log > ...0)]shifted(-wid/2,0)rotated(angle(ad)) metapost log > shifted.ap;draw.pic[(EXPR0... metapost log > <argument> ...caled0.5pt.withcolor.green;fi;endfor metapost log > ;if((autoscaleupfollowtext... metapost log > metapost log > image->...ture;currentpicture:=nullpicture;(TEXT3) metapost log > ;currentpicture.if.str(SUF... metapost log > metapost log > followtext->...b_n;setbounds.currentpicture.to.b;) metapost log > endgroup metapost log > <argument> ...parameter"path"),getparameter"text") metapost log > ;popparameters; metapost log > image->...ture;currentpicture:=nullpicture;(TEXT3) metapost log > ;currentpicture.if.str(SUF... metapost log > metapost log > lmt_do_followtext->...meter"text");popparameters;) metapost log > endgroup metapost log > <scantokens> lmt_do_followtext metapost log > metapost log > <*> ...exstring, path = parpath, spread = false, ] metapost log > ; ; When I adapt the parameters that create parpath in my code, other uses of lmt_followtext crash. The same combinations of text and path so far haven’t crashed basic followtext(). I’ve run into comparable situations in my own code where I had to add code to handle the existence of a (0,0) direction (e.g. when I had two identical points on a path, but that is not the case here). The above minimal example triggers the failure. G