>> Meanwhile, the Satimage "find text" is also producing errors, again
>> when the target string is not present.
You could use regexps that find nothing if that is what is present
find text "[123]*$" in "1345" with regexp
--> {matchPos:4, matchLen:0, matchResult:""}
However failing to find something (that is missing) might be an error in the
unput data. You just trap it.
try
find text "[123]+$" in "1345" with regexp
on error m
display dialog m
end try