jdk.nashorn.internal.runtime.ECMAException: ReferenceError: "a" is not defined
	at jdk.nashorn.internal.runtime.ECMAErrors.error(ECMAErrors.java:57)
	at jdk.nashorn.internal.runtime.ECMAErrors.referenceError(ECMAErrors.java:319)
	at jdk.nashorn.internal.runtime.ECMAErrors.referenceError(ECMAErrors.java:291)
	at jdk.nashorn.internal.runtime.ECMAErrors.referenceError(ECMAErrors.java:278)
	at jdk.nashorn.internal.runtime.ScriptObject.noSuchProperty(ScriptObject.java:2379)
	at jdk.nashorn.internal.runtime.ScriptObject.findGetMethod(ScriptObject.java:1989)
	at jdk.nashorn.internal.runtime.ScriptObject.lookup(ScriptObject.java:1850)
	at jdk.nashorn.internal.runtime.linker.NashornLinker.getGuardedInvocation(NashornLinker.java:100)
	at jdk.nashorn.internal.runtime.linker.NashornLinker.getGuardedInvocation(NashornLinker.java:94)
	at jdk.internal.dynalink.support.CompositeTypeBasedGuardingDynamicLinker.getGuardedInvocation(CompositeTypeBasedGuardingDynamicLinker.java:176)
	at jdk.internal.dynalink.support.CompositeGuardingDynamicLinker.getGuardedInvocation(CompositeGuardingDynamicLinker.java:124)
	at jdk.internal.dynalink.support.LinkerServicesImpl.getGuardedInvocation(LinkerServicesImpl.java:154)
	at jdk.internal.dynalink.DynamicLinker.relink(DynamicLinker.java:234)
	at jdk.nashorn.internal.scripts.Script$2$\^eval\_.:program(<eval>:1)
	at jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:636)
	at jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:228)
	at jdk.nashorn.internal.runtime.ScriptRuntime.apply(ScriptRuntime.java:393)
	at jdk.nashorn.internal.runtime.Context.eval(Context.java:745)
	at jdk.nashorn.internal.runtime.Context.eval(Context.java:675)
	at jdk.nashorn.internal.scripts.Script$Recompilation$1$13$EvalTest.L:2(EvalTest.js:11)
	at jdk.nashorn.internal.scripts.Script$EvalTest.:program(EvalTest.js:2)
	at jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:636)
	at jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:228)
	at jdk.nashorn.internal.runtime.ScriptRuntime.apply(ScriptRuntime.java:393)
	at jdk.nashorn.tools.Shell.apply(Shell.java:397)
	at jdk.nashorn.tools.Shell.runScripts(Shell.java:326)
	at jdk.nashorn.tools.Shell.run(Shell.java:172)
	at jdk.nashorn.tools.Shell.main(Shell.java:136)
	at jdk.nashorn.tools.Shell.main(Shell.java:112)