I think the current behaviour is correct and the parser works as-is.

get *a(){} is never allowed in the MethodDefinition production, so the token * becomes the offending token per rules of ASI, since * is separated from the previous token by a line break, ASI is applied and therefore get becomes get; which is then parsed as a class property.

class A2 {
  get
  *a(){}
}
const a2 = new A2();
console.log(a2.a);
console.log("get" in a2);

The browser seems to accept the form like this, whereas TypeScript complains about it.

Oh and Firefox rejects that code. I'll investigate a bit more and report the appropriate bugs.

I submitted a test262 test: tc39/test262#4189