1 undefined undefined 0
   2 ReferenceError: "x" is not defined
   3 z: 1
   4 assignment to z succeeded
   5 ReferenceError: "z" is not defined
   6 1
   7 assignment to a succeeded
   8 a: 1
   9 b: 1
  10 assignment to b succeeded
  11 b: 1
  12 TypeError: "c" is not a writable property of [object Object]
  13 c: 0
  14 2 1 0
  15 2 1 0 undefined
  16 undefined undefined undefined undefined undefined
  17 v: 1
  18 v: 2
  19 this.v: undefined
  20 v: 2