(x) => x + 1 causes Assertion failure instead of SyntaxError

jjs> (x) => x + 1
Exception in thread "main" java.lang.AssertionError: Failed generating bytecode for <shell>:1
at jdk.nashorn.internal.codegen.CompilationPhase$BytecodeGenerationPhase.transform(jdk.scripting.nashorn@9.0/CompilationPhase.java:436)
at jdk.nashorn.internal.codegen.CompilationPhase.apply(jdk.scripting.nashorn@9.0/CompilationPhase.java:630)
at jdk.nashorn.internal.codegen.Compiler.compile(jdk.scripting.nashorn@9.0/Compiler.java:656)
at jdk.nashorn.internal.runtime.RecompilableScriptFunctionData.compileTypeSpecialization(jdk.scripting.nashorn@9.0/RecompilableScriptFunctionData.java:717)
at jdk.nashorn.internal.runtime.RecompilableScriptFunctionData.getBest(jdk.scripting.nashorn@9.0/RecompilableScriptFunctionData.java:897)
at jdk.nashorn.internal.runtime.ScriptFunctionData.getGeneric(jdk.scripting.nashorn@9.0/ScriptFunctionData.java:370)
at jdk.nashorn.internal.runtime.ScriptFunctionData.createGenericInvoker(jdk.scripting.nashorn@9.0/ScriptFunctionData.java:282)
at jdk.nashorn.internal.runtime.ScriptFunctionData.getGenericInvoker(jdk.scripting.nashorn@9.0/ScriptFunctionData.java:276)
at jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(jdk.scripting.nashorn@9.0/ScriptFunctionData.java:606)
at jdk.nashorn.internal.runtime.ScriptFunction.invoke(jdk.scripting.nashorn@9.0/ScriptFunction.java:511)
at jdk.nashorn.internal.runtime.ScriptRuntime.apply(jdk.scripting.nashorn@9.0/ScriptRuntime.java:394)
at jdk.nashorn.internal.runtime.Context.eval(jdk.scripting.nashorn@9.0/Context.java:829)
at jdk.nashorn.internal.runtime.Context.eval(jdk.scripting.nashorn@9.0/Context.java:764)
at jdk.nashorn.tools.jjs.Main.readEvalPrint(jdk.scripting.nashorn.shell@9.0/Main.java:166)
at jdk.nashorn.tools.Shell.run(jdk.scripting.nashorn@9.0/Shell.java:166)
at jdk.nashorn.tools.jjs.Main.main(jdk.scripting.nashorn.shell@9.0/Main.java:91)
at jdk.nashorn.tools.jjs.Main.main(jdk.scripting.nashorn.shell@9.0/Main.java:67)
Caused by: java.lang.AssertionError: jdk.nashorn.internal.ir.BinaryNode
at jdk.nashorn.internal.codegen.CodeGenerator$2.enterDefault(jdk.scripting.nashorn@9.0/CodeGenerator.java:1231)
at jdk.nashorn.internal.ir.visitor.NodeOperatorVisitor.enterBIND(jdk.scripting.nashorn@9.0/NodeOperatorVisitor.java:744)
at jdk.nashorn.internal.ir.visitor.NodeOperatorVisitor.enterBinaryNode(jdk.scripting.nashorn@9.0/NodeOperatorVisitor.java:137)
at jdk.nashorn.internal.ir.BinaryNode.accept(jdk.scripting.nashorn@9.0/BinaryNode.java:339)
at jdk.nashorn.internal.codegen.CodeGenerator.loadExpression(jdk.scripting.nashorn@9.0/CodeGenerator.java:862)
at jdk.nashorn.internal.codegen.CodeGenerator.loadExpression(jdk.scripting.nashorn@9.0/CodeGenerator.java:838)
at jdk.nashorn.internal.codegen.CodeGenerator.loadExpressionAsType(jdk.scripting.nashorn@9.0/CodeGenerator.java:834)
at jdk.nashorn.internal.codegen.CodeGenerator$16.evaluate(jdk.scripting.nashorn@9.0/CodeGenerator.java:3888)
at jdk.nashorn.internal.codegen.CodeGenerator$Store.store(jdk.scripting.nashorn@9.0/CodeGenerator.java:4505)
at jdk.nashorn.internal.codegen.CodeGenerator.loadASSIGN(jdk.scripting.nashorn@9.0/CodeGenerator.java:3890)
at jdk.nashorn.internal.codegen.CodeGenerator.access$900(jdk.scripting.nashorn@9.0/CodeGenerator.java:178)
at jdk.nashorn.internal.codegen.CodeGenerator$2.enterASSIGN(jdk.scripting.nashorn@9.0/CodeGenerator.java:924)
at jdk.nashorn.internal.ir.visitor.NodeOperatorVisitor.enterBinaryNode(jdk.scripting.nashorn@9.0/NodeOperatorVisitor.java:113)
at jdk.nashorn.internal.ir.BinaryNode.accept(jdk.scripting.nashorn@9.0/BinaryNode.java:339)
at jdk.nashorn.internal.codegen.CodeGenerator.loadExpression(jdk.scripting.nashorn@9.0/CodeGenerator.java:862)
at jdk.nashorn.internal.codegen.CodeGenerator.loadExpression(jdk.scripting.nashorn@9.0/CodeGenerator.java:838)
at jdk.nashorn.internal.codegen.CodeGenerator.loadAndDiscard(jdk.scripting.nashorn@9.0/CodeGenerator.java:3681)
at jdk.nashorn.internal.codegen.CodeGenerator.enterExpressionStatement(jdk.scripting.nashorn@9.0/CodeGenerator.java:1728)
at jdk.nashorn.internal.ir.ExpressionStatement.accept(jdk.scripting.nashorn@9.0/ExpressionStatement.java:63)
at jdk.nashorn.internal.ir.Node.accept(jdk.scripting.nashorn@9.0/Node.java:286)
at jdk.nashorn.internal.ir.Block.accept(jdk.scripting.nashorn@9.0/Block.java:214)
at jdk.nashorn.internal.ir.LexicalContextNode$Acceptor.accept(jdk.scripting.nashorn@9.0/LexicalContextNode.java:57)
at jdk.nashorn.internal.ir.Block.accept(jdk.scripting.nashorn@9.0/Block.java:477)
at jdk.nashorn.internal.ir.FunctionNode.accept(jdk.scripting.nashorn@9.0/FunctionNode.java:343)
at jdk.nashorn.internal.ir.LexicalContextNode$Acceptor.accept(jdk.scripting.nashorn@9.0/LexicalContextNode.java:57)
at jdk.nashorn.internal.ir.LexicalContextExpression.accept(jdk.scripting.nashorn@9.0/LexicalContextExpression.java:47)
at jdk.nashorn.internal.ir.FunctionNode.accept(jdk.scripting.nashorn@9.0/FunctionNode.java:56)
at jdk.nashorn.internal.codegen.CompilationPhase.transformFunction(jdk.scripting.nashorn@9.0/CompilationPhase.java:634)
at jdk.nashorn.internal.codegen.CompilationPhase.access$100(jdk.scripting.nashorn@9.0/CompilationPhase.java:55)
at jdk.nashorn.internal.codegen.CompilationPhase$BytecodeGenerationPhase.transform(jdk.scripting.nashorn@9.0/CompilationPhase.java:423)
... 16 more