nl_tokens: Checks whether the trap result is consistent with the state of the wrapped target .
pl_tokens: function ( ) { var trap = this . getTrap ( "isSealed" ) ; if ( trap === undefined ) { // default forwarding behavior return Reflect . isSealed ( this . target ) ; } var result = trap . call ( this . handler , this . target ) ; result = ! ! result ; // coerce to Boolean var state = Object_isSealed ( this . target ) ; if ( result !== <mask> ) { if ( result ) { throw new TypeError ( "cannot report unsealed object as sealed: " + this . target ) ; } else { throw new TypeError ( "cannot report sealed object as unsealed: " + this . target ) ; } } return state ; }