147, The Gemara in Shabbos quotes Rav Yosef wishing that he will have a Chelek with those who died Biderech Mitzva.
One possible approach is that Sheluchei Mitzva Einan Nizakin is a rule that means the person won’t get hurt becase of performing a Mitzva unless there was a reasonable risk involved. The person can still get hurt by any other means that would have happened regardless.