React. this.setState is not a function inside setTimeout [duplicate]

You are loosing context. Use arrow function as simple way to preserve proper execution context:

setTimeout(() => {
  this.setState({breaker: false});
}, 2000)

Remember that anonymous function will have context window inside, unless you explicitly bind it with Function.prototype.bind. So here is another way to solve this problem:

setTimeout(function () {
  this.setState({breaker: false});
}.bind(this), 2000)