A DESCRIPTION OF THE PROBLEM :
Variable declared and used in scope of nested function is not accessible when
eval is used in the function (does not need to be executed)
and
a RewriteException is handled as a consequence of UnwarrantedOptimismException.
Related community threads:
https://stackoverflow.com/questions/61613216/nashorn-es6-corrupted-function-scope

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. create nashorn engine with es6 language level features
2. compile and execute script:
function fn() {
    const object1 = { "name": "Pepa" };
    print(object1.name);
    const descriptor1 = Object.getOwnPropertyDescriptor(object1, 'name');
    print(descriptor1.configurable);
    print(eval("3+1"));
}
fn();

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Script execution successful without Exception
Output:
Pepa
true
4
ACTUAL -
Exception in thread "main" javax.script.ScriptException: ReferenceError: "descriptor1" is not defined in <eval> at line number 8

---------- BEGIN SOURCE ----------
import jdk.nashorn.api.scripting.NashornScriptEngineFactory;

import javax.script.Compilable;
import javax.script.ScriptException;

public class MainJava {
    public static void main(String[] args) throws ScriptException {
        var brokenScript = String.join("\n",
                "function fn() {",
                "const object1 = { 'name': 'Pepa' };",
                "print(object1.name);",
                "const descriptor1 = Object.getOwnPropertyDescriptor(object1, 'name');",
                "print(descriptor1.configurable);",
                "print(eval('3+1'));",
                "}",
                "fn();"
        );
        var factory = new NashornScriptEngineFactory();
        var engine = (Compilable) factory.getScriptEngine("--no-deprecation-warning", "--language=es6", "--log=compiler:finest,fields,recompile:fine");
        var script = engine.compile(brokenScript);
        script.eval();
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Rewrite the script to either
- not use eval in the nested function
- declare variables as var instead of const
- avoid UnwarrantedOptimismException (here caused by execution of Object.getOwnPropertyDescriptor)

FREQUENCY : always