While we will all die someday, it is completely appropriate to ask God that he will spare you a sudden death.
Death is part of being human, and while we should be prepare to die on a daily basis, it is still understandable why you wouldn’t want to die a sudden or unforeseen death.
It is a great gift to be on your deathbed, able to see friends and family, reconciling with those you love. Not everyone is given such a gift. Some will die in a car accident or some other event that leaves little time to prepare.
If we are still not ready to die, the Church finds it legitimate to ask God to stay his hand for a while, giving you a little extra time to prepare for that day.
Here is a petition from the Litany of the Saints that is quoted in the Catechism of the Catholic Church. It can be prayed often and even included in your daily prayers, hoping that it is in God’s will to give you the gift of a well-prepared death.
From a sudden and unforeseen death, deliver us, O Lord