removeFromArrayAndUpdateIndex

        fn removeFromArrayAndUpdateIndex(self: *Self, entry_index: usize, ctx: ByIndexContext, header: *IndexHeader, comptime I: type, indexes: []Index(I), comptime removal_type: RemovalType) void {
            const last_index = self.entries.len - 1; // overflow => remove from empty map
            switch (removal_type) {
                .swap => {
                    if (last_index != entry_index) {
                        // Because of the swap remove, now we need to update the index that was
                        // pointing to the last entry and is now pointing to this removed item slot.
                        self.updateEntryIndex(header, last_index, entry_index, ctx, I, indexes);
                    }
                    // updateEntryIndex reads from the old entry index,
                    // so it needs to run before removal.
                    self.entries.swapRemove(entry_index);
                },
                .ordered => {
                    var i: usize = entry_index;
                    while (i < last_index) : (i += 1) {
                        // Because of the ordered remove, everything from the entry index onwards has
                        // been shifted forward so we'll need to update the index entries.
                        self.updateEntryIndex(header, i + 1, i, ctx, I, indexes);
                    }
                    // updateEntryIndex reads from the old entry index,
                    // so it needs to run before removal.
                    self.entries.orderedRemove(entry_index);
                },
            }
        }