hmm, we are probably missing few paths in our sun.jdk module to make this work properly.
add open WILDFLY_HOME\modules\system\layers\base\sun\jdk\main\module.xml
other thing you can do is open
and remove the one that gives you problems.
Also looking trough the code/docs of ScriptEngineManager, that error message is only informative nature.
You still get back one engine, and that is rhino or nashorn depending on what JDK you are on.
JDK should probably have better error reporting in this case or none at all.
In any case removing entry from javax.script.ScriptEngineFactory will make that problem go away, but you will need to modify every time you switch JDK.