insertEntryIntoNewHeaderGeneric

        fn insertEntryIntoNewHeaderGeneric(header: *IndexHeader, h: u32, i: usize, comptime I: type) void {
            const indexes = header.indexes(I);
            const start_index = safeTruncate(usize, h);
            const end_index = start_index +% indexes.len;
            var index = start_index;
            var entry_index: I = @intCast(i);
            var distance_from_start_index: I = 0;
            while (index != end_index) : ({
                index +%= 1;
                distance_from_start_index += 1;
            }) {
                const slot = header.constrainIndex(index);
                const next_index = indexes[slot];
                if (next_index.isEmpty()) {
                    indexes[slot] = .{
                        .distance_from_start_index = distance_from_start_index,
                        .entry_index = entry_index,
                    };
                    return;
                }
                if (next_index.distance_from_start_index < distance_from_start_index) {
                    indexes[slot] = .{
                        .distance_from_start_index = distance_from_start_index,
                        .entry_index = entry_index,
                    };
                    distance_from_start_index = next_index.distance_from_start_index;
                    entry_index = next_index.entry_index;
                }
            }
            unreachable;
        }