Our Japanese collegues suffered such a cases twice, in 1905 on BB Mikasa and in 1943 on BB Mutsu. First case was not about the firing but was connected with the sailors' striving for alcohol which they tried to get from the signal flares by boiling and occasionally fired the powder of 6" guns. On big gun ships it's always the risk of an explosion of the powder magazines existed. While USN has thankfully escaped the missiles' disasters, the Soviet Navy had lost the DD Otvagny ("Courageuos") in 1974 due to the anti-air missiles explosion, namely booster of one missile (NATO SA-N-1 Goa) had been started while in magazine.