Some say that the eleventh Imam of the Shiites, Al-Hassan Al-Askari, died without leaving a son. However, in…

Some say that the eleventh Imam of the Shiites, Al-Hassan Al-Askari, died without leaving a son. However, in order not to lose the foundations of the Imami sect, a man named (Othman Ibin Saeed) claimed that Al-Askari had a son who disappeared when he was four years old, and that was his representative. How strange that the Shiites claim that they only accept the sayings of the infallible and here they accept, in their most important beliefs, the claim of one fallible man?