Just found this out.
so in the first Thor Odin states the hammer was forged in the 'heart of a dying star' as a clear reference to the comics and also establishing the power the weapon/tool has. But in Infinity War Thor states it was forged in the 'heart of a blazing neutron star' small difference but big effect.
See when a giant star reaches supernova the gravitational collapse causes it to turn into a black hole. However if the star is not large enough after the supernova it will form into neutron star.
This I why the dwarves are not worried about it exploding because it already has and the star will just get colder over millions of years to the point where there is no more radiation for it to emit.