#319 SET IDLINE OFF results in "Assertion failed!"

[m-stgt]

Installed THE under Win10 Pro (UTF-8 enabled) with THE40w64_ooRexx.exe, using profile (work in progress)

/* profile.therc -- THE profile */
COMPAT X X X
case m i i i m m
curl 5
tabl off
scale on 1
AUTOCOLOR "*.rx rexx"
DEFSORT D
HEXDISP ON
/* some colours */
colour gap y blu
colour cgap y y

testing interactively SET IDline OFF removes 'F' from 'OFF' and shows message as attached