The following code either gives an error message or crashes the interpreter. Error/crash happens after an arbitrary number of loops (in the range of a few ten thousand). It crashes for me after approx. 15 seconds. This stripped-down code isn't "stable" in the sense that a small change will make it run forever without error.
rexx -e "call Read; exit; Read: F='DoesntExist'; Open=stream(F,'C','OPEN READ'); do until Line<>''; Line=linein(F); end; return"
The crash message says "Open Object Rexx Interface has stopped working"
Alternatively I've seen this error message (original, not stripped-down code):
*-* Compiled routine LINEIN 94 *-* Line=linein(F) 59 *-* call Read Error 97: Object method not found Error 97.1: Object "NOTREADY" does not understand message "=="