Contract storage issue

[RomanKytseniuk]

The error appears when I try to store data in Map: u256 => Custom_struct.

write_at_offset offset: 1, value: 0
write_at_offset offset: 7, value: 343251015074091674243752244076765003151029070702005464048520849265061698326
write_at_offset offset: 8, value: 0
write_at_offset offset: 9, value: 1
write_at_offset offset: 10, value: 0
write_at_offset offset: 11, value: 1
write_at_offset offset: 12, value: 12340
write_at_offset offset: 13, value: 2
write_at_offset offset: 14, value: 1780377514174794913857483948528551232962667070437803314071575017214746865917
write_at_offset offset: 15, value: 1780377514174794913857483948528551232962667070437803314071575017214746865917

i got two more Span to store but owerflow appear

[FAIL] tests::test_store_struct
Failure data:
0x75385f616464204f766572666c6f77 ('u8_add Overflow')

Please check this small example and run by

snforge test

https://github.com/RomanKytseniuk/starknet_struct_error/blob/main/src/lib.cairo

I know that I should use Vec, but the error appears anyway