Outside of extremely extenuating circumstances, this isn’t a worry. We already have proof-of-concept tech like DART to divert asteroids, aerospace engineers can use this to get governments to fund them even better, asteroid goes behind the sun for 3 years, asteroid diverting technology advances even further, in 2028 when the path of travel becomes more precise the chance of hitting us gets revised down to zero, and we’ve advanced our technology should anything more serious come our way in the future