The following script:

(1)[0]

throws this:

Exception in thread "main" java.lang.AssertionError: int is not compatible with object
at jdk.nashorn.internal.codegen.MethodEmitter.popType(MethodEmitter.java:231)
at jdk.nashorn.internal.codegen.MethodEmitter.dynamicGetIndex(MethodEmitter.java:1873)
at jdk.nashorn.internal.codegen.CodeGenerator$1.enter(CodeGenerator.java:347)
at jdk.nashorn.internal.ir.IndexNode.accept(IndexNode.java:95)
at jdk.nashorn.internal.codegen.CodeGenerator.load(CodeGenerator.java:324)
at jdk.nashorn.internal.codegen.CodeGenerator.load(CodeGenerator.java:305)
at jdk.nashorn.internal.codegen.CodeGenerator$8.evaluate(CodeGenerator.java:2409)
at jdk.nashorn.internal.codegen.CodeGenerator$Store.store(CodeGenerator.java:3199)
at jdk.nashorn.internal.codegen.CodeGenerator.enterASSIGN(CodeGenerator.java:2411)
at jdk.nashorn.internal.ir.visitor.NodeOperatorVisitor.enter(NodeOperatorVisitor.java:129)
at jdk.nashorn.internal.ir.BinaryNode.accept(BinaryNode.java:176)
at jdk.nashorn.internal.codegen.CodeGenerator$1.enterDefault(CodeGenerator.java:353)
at jdk.nashorn.internal.ir.visitor.NodeVisitor.enter(NodeVisitor.java:197)
at jdk.nashorn.internal.ir.BinaryNode.accept(BinaryNode.java:176)
at jdk.nashorn.internal.codegen.CodeGenerator.load(CodeGenerator.java:324)
at jdk.nashorn.internal.codegen.CodeGenerator.load(CodeGenerator.java:305)
at jdk.nashorn.internal.codegen.CodeGenerator.enterDISCARD(CodeGenerator.java:2260)
at jdk.nashorn.internal.ir.visitor.NodeOperatorVisitor.enter(NodeOperatorVisitor.java:67)
at jdk.nashorn.internal.ir.UnaryNode.accept(UnaryNode.java:145)
at jdk.nashorn.internal.codegen.CodeGenerator.enter(CodeGenerator.java:767)
at jdk.nashorn.internal.ir.ExecuteNode.accept(ExecuteNode.java:80)
at jdk.nashorn.internal.ir.FunctionNode.accept(FunctionNode.java:309)
at jdk.nashorn.internal.codegen.Compiler.compile(Compiler.java:377)
at jdk.nashorn.internal.runtime.Context.compile(Context.java:827)
at jdk.nashorn.internal.runtime.Context.compile(Context.java:807)
at jdk.nashorn.internal.runtime.Context.eval(Context.java:500)
at jdk.nashorn.tools.Shell.readEvalPrint(Shell.java:375)
at jdk.nashorn.tools.Shell.run(Shell.java:160)
at jdk.nashorn.tools.Shell.main(Shell.java:136)
at jdk.nashorn.tools.Shell.main(Shell.java:115)

This should compile and run (see ES 11.2.1 Property Accessors)