scancode crashing objc[59417]: +[__NSCFConstantString initialize] may have been in progress in another thread when fork() was called.

Env is:
OS: macOS High Sierra 10.13
scancode-toolkit version: 2.2.1

```
/usr/local/scancode-toolkit-2.2.1/scancode --format html-app --diag -n 10 --ignore "lib/*" --ignore "out/*" --ignore "build/*" --ignore "*.war" --ignore "*.tgz" --ignore "*.zip" --ignore "*.jar" --ignore "*/node_modules/*" --ignore "*.pdf" --ignore "*.jpg" --ignore "*.png" --ignore "*.csv" . oss-report.html
Scanning files for: licenses, copyrights, packages with 10 process(es)...
Building license detection index...Done.
Scanning files...
[---------------#----] 8613 Scanned: Spacer.js objc[59121]: +[__NSCFConstantString initialize] may have been in progress in another thread when fork() was called.
objc[59121]: +[__NSCFConstantString initialize] may have been in progress in another thread when fork() was called. We cannot safely call it or ignore it in the fork() child process. Crashing instead. Set a breakpoint on objc_initializeAfterForkError to debug.

```