The code can't determine the value?

Question

Google Sheets

Rarely, but it happens that the code cannot determine the value from another site. It happens 1 to 100. Code =REGEXEXTRACT(INDEX( IMPORTHTML
(G99;"table";0);2;1);".*?\d+\s*\-.*?(\d+)")
which the problem occurs
https://readmanga.me/vosstavshii_protiv_deviati_nebes
https://readmanga.me/pererojdenie_istochennogo__ma...
https://readmanga.me/different_world_hospitality_meals
If you know the answer, then write what it is connected with and how to solve it.
Note: When hovering over an error, it displays an internal import error message.

Answer 1

solve: repeat request
channels is not something permanent, data is not guaranteed