stress-inode-flags reports errno 13 but does not report a failure in termination

stress-ng-inode-flags reports, variously, the following errors:

stress-ng: 12:27:12.67 error: [32322] stress-ng-inode-flags: cannot open ./tmp-stress-ng-inode-flags-32322-3/stress-ng-inode-flags-32322-3-2060495061: errno=13 (Permission denied)

stress-ng: 16:38:13.65 error: [9810] stress-ng-inode-flags: cannot open ./tmp-stress-ng
-inode-flags-9810-0/stress-ng-inode-flags-9810-0-3340326306: errno=13 (Permission denied)
stress-ng: 16:38:13.65 error: [9810] stress-ng-inode-flags: cannot open ./tmp-stress-ng
-inode-flags-9810-0/stress-ng-inode-flags-9810-0-3340326306: errno=13 (Permission denied)
stress-ng: 16:38:13.65 error: [9810] stress-ng-inode-flags: cannot open ./tmp-stress-ng
-inode-flags-9810-0/stress-ng-inode-flags-9810-0-3340326306: errno=13 (Permission denied)
stress-ng: 16:38:13.65 error: [9810] stress-ng-inode-flags: cannot open ./tmp-stress-ng-inode-flags-9810-0/stress-ng-inode-flags-9810-0-3340326306: errno=13 (Permission denied)

stress-ng: 16:39:29.62 error: [31148] stress-ng-inode-flags: cannot open ./tmp-stress-ng-inode-flags-31148-0/stress-ng-inode-flags-31148-0-1846194840: errno=1 (Operation not permitted)
stress-ng: 16:39:29.62 error: [31148] stress-ng-inode-flags: cannot open ./tmp-stress-ng-inode-flags-31148-0/stress-ng-inode-flags-31148-0-1846194840: errno=1 (Operation not permitted)
stress-ng: 16:39:29.62 error: [31148] stress-ng-inode-flags: cannot open ./tmp-stress-ng-inode-flags-31148-0/stress-ng-inode-flags-31148-0-1846194840: errno=1 (Operation not permitted)
stress-ng: 16:39:29.62 error: [31148] stress-ng-inode-flags: cannot open ./tmp-stress-ng-inode-flags-31148-0/stress-ng-inode-flags-31148-0-1846194840: errno=1 (Operation not permitted)
stress-ng: 16:39:29.62 error: [31148] stress-ng-inode-flags: cannot open ./tmp-stress-ng-inode-flags-31148-0/stress-ng-inode-flags-31148-0-1846194840: errno=1 (Operation not permitted)

stress-ng: 18:16:19.73 error: [30507] stress-ng-inode-flags: cannot open ./tmp-stress-ng-inode-flags-30507-1/stress-ng-inode-flags-30507-1-1821874951: errno=1 (Operation not permitted)

stress-ng: 18:28:15.68 error: [32528] stress-ng-inode-flags: cannot open ./tmp-stress-ng-inode-flags-32528-1/stress-ng-inode-flags-32528-1-1344360964: errno=1 (Operation not permitted)

(Having separated by spaces the messages from different runs.)

If I understand correctly, in stress-ng's terminology, "error:" means something more like a bug in stress-ng itself, rather than a problem it found with the system?

Using stress-ng-0.10