Why was Shri Krishna killed by a hunter?

Lord Krishna is the epitome of divine love and wisdom. He is worshipped by people all over the world, not just Hindus, but also those who fell in love with Krishna leela. Shri Krishna, who grew up in the small Gokul, soon enchanted everyone around him and his leelas were famous all over. From lifting the mighty Govardhan hill to making people fall in love with his divine flute melodies, he did it all.

Lord Krishna was the charioteer for Arjun during the war of Mahabharat. Gandhari, the mother of the Kauravas, developed deep anger and resentment towards Krishna following the war for he helped the Pandavas kill the Kauravas. Blaming him for the loss of her sons, Gandhari placed a curse on Krishna that in the next 36 years all his clan will kill themselves and he too will watch helplessly. Krishna's entire clan, the Yadavas, faced a descent into madness.

Gandhari’s curse was starting to turn into reality. And soon the Yadavas, who were successful and living in bliss, started to forget their morality and ethics and engaged in unethical practices. While Krishna saw it all, he did not intervene for it was the divine plan unfolding in front of him. Soon, there were internal strifes and conflicts and the prosperous kingdom was on the verge of extinction.
A few men from the community, drunk, started hurling abuses at each other first for fun, but then it escalated and near a river they killed each other. Soon, the clan vanished.

Looking at the doom of his clan, Shri Krishna knew that Gandhari’s curse was turning to reality. He also knew that this was his clue that it is time for him to leave this world and depart to Vaikuntha. And so, he made the decision of retreating to the forest and engaging in deep meditation till death engulfs him.

As Krishna sat in the forest meditating he was still as a statue. And in the meanwhile, a hunter, Jara, was looking for an animal. Mistaking Krishna’s feet for an animal, Jara struck his arrow at him and pierced Krishna’s feet. Realising his mistake, Jara ran towards Krishna to apologise to him but was met with the realisation that Krishna’s death was inevitable during this time and it was Jara who enabled him to depart towards Vaikuntha.