Angular 2 SimpleChanges Object throws error at first npm start

To make the compiler not complain just change your method definition for parameter one from SimpleChanges to any:

ngOnChanges(changes: any) {

//...

The accepted solution is suboptimal for TypeScript, as you're defeating the type system.

SimpleChanges does not have an entry property, so the compiler quite rightly balks. The solution is to treat the changes object as an array:

ngOnChanges(changes : SimpleChanges){
  if (changes['entry']) {
    this.service.getComments(changes['entry'].currentValue.id)
  }
}

Then you can continue to strongly type the ngOnChanges method.