removeFromIndexByKey

        fn removeFromIndexByKey(self: *Self, key: anytype, ctx: anytype, header: *IndexHeader, comptime I: type, indexes: []Index(I)) ?usize {
            const slot = self.getSlotByKey(key, ctx, header, I, indexes) orelse return null;
            const removed_entry_index = indexes[slot].entry_index;
            removeSlot(slot, header, I, indexes);
            return removed_entry_index;
        }