The authorities have put up a no-go zone cordon around the volcano, and all hiking tours have been cancelled. So keep your distance from Mt Agung and there's no reason to worry about safety. Krakatoa-size eruptions are extremely rare... it's not like all of Bali will disappear in a puff of smoke.
Be aware though, that depending on prevailing winds and an ash cloud, air traffic in and out of Bali may be disrupted. It happened a couple of years ago and flights were cancelled for weeks. Check that your insurance policy covers delay and cancellation from a volcano. over 2 years ago