fix: msg_stamp.size() is unsigned,should convert to int (#2523)

TouchZZZ

2025-05-22 eccf74684743593950ad259877db7ce9ffc06e93

1
2
3
4
5
6
7
8
9
x    1
xx    2
xxx    3
xl    4
l    5
lx    6
lxx    7
lxxx    8
xc    9