By Felix Keith West Ham supporters have been left furious after the referee missed a potential red card just five minutes into their FA Cup defeat against Bristol City. The Hammers were knocked out in the third round replay on Tuesday night, with Tommy Conway’s early goal enough for the Championship side to win it 1-0. David Moyes ’ side played most of the second half with 10 men after Said Benrahma was sent off for kicking out at Joe Williams following a foul. But many West Ham fans felt Williams should not have even been on the pitch following a heavy challenge on Danny Ings in the fifth min…