[jsscripting] Fix memory leak on script execution failure

[florian-h05]

Add-on part of the fix for #16462.

[florian-h05]

@jlaur I have now pushed my improvement. It basically stringifies the first 5 elements of the stack trace (that should be enough for the JS part of the stack trace in most cases) so we still have a part of the stack trace, but Pax Logging does not hold a ref to the exception. I have also checked this change again with VisualVM, it does not re-introduce the memory leak.

FYI I also made the engine identifier an instance field for OpenhabGraalJSScriptEngine because it really really eases debugging.

[florian-h05]

The log message now looks like:

11:46:55.591 [ERROR] [.automation.script.javascript.abcd.js] - Failed to execute script: SyntaxError: abcd.js:10:97 Expected } but found eof
{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{};{
                                                                                                 ^
        at org.graalvm.polyglot.Context.eval(Context.java:399)
        at com.oracle.truffle.js.scriptengine.GraalJSScriptEngine.eval(GraalJSScriptEngine.java:458)
        at com.oracle.truffle.js.scriptengine.GraalJSScriptEngine.eval(GraalJSScriptEngine.java:400)
        at java.scripting/javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:247)
        at org.openhab.automation.jsscripting.internal.scriptengine.DelegatingScriptEngineWithInvocableAndAutocloseable.eval(DelegatingScriptEngineWithInvocableAndAutocloseable.java:57)
        ... 18 more

And if there is a JS stack trace:

11:49:13.424 [ERROR] [tomation.script.javascript.a299db5278] - Failed to execute script: Error
        at <js>.getItem(/etc/openhab/automation/js/node_modules/openhab/src/items/items.js:589)
        at <js>.:program(<eval>:1)
        at org.graalvm.polyglot.Context.eval(Context.java:399)
        at com.oracle.truffle.js.scriptengine.GraalJSScriptEngine.eval(GraalJSScriptEngine.java:458)
        at com.oracle.truffle.js.scriptengine.GraalJSScriptEngine.eval(GraalJSScriptEngine.java:426)
        ... 76 more

[jlaur]

Many thanks for fixing this nasty memory leak!