interp: make trap consistent with errexit logic

This implementation already excludes conditional contexts
for exiting on error when errexit is set; it should be
consistent with reporting errors to a trap routine.

interp/interp_test.go

@@ -2156,6 +2156,7 @@ set +o pipefail
 	// trap
 	{"trap 'echo at_exit' EXIT; true", "at_exit\n"},
 	{"trap 'echo on_err' ERR; false; echo FAIL", "on_err\nFAIL\n"},
+	{"trap 'echo on_err' ERR; false || true; echo OK", "OK\n"},
 	{"trap 'echo at_exit' EXIT; trap - EXIT; echo OK", "OK\n"},
 	{"set -e; trap 'echo A' ERR EXIT; false; echo FAIL", "A\nA\nexit status 1"},
 	{"trap 'foo_interp_missingbar_interp_missing' UNKNOWN", "trap: UNKNOWN: invalid signal specification\nexit status 2 #JUSTERR"},

interp/runner.go

@@ -311,7 +311,7 @@ func (r *Runner) stmtSync(ctx context.Context, st *syntax.Stmt) {
 		//   part of && or || lists
 		//   preceded by !
 		r.exitShell(ctx, r.exit)
-	} else if r.exit != 0 {
+	} else if r.exit != 0 && !r.noErrExit {
 		r.trapCallback(ctx, r.callbackErr, "error")
 	}
 	if !r.keepRedirs {