How did Li Mao, the longevity prince, die?

Official history died of natural causes. In the Book of the New Tang Dynasty, Wang Huan, the lifesaver, whose mother, Hui Fei, was born after repeated infertility. Wang Ning invited her to stay in the mansion, and Yuan Fei named her as her own son, so she was named the last child. In the fifteenth year of Kaiyuan, he led the governor of Yizhou from afar. At the beginning, the emperor was still young, such as Wang Yong, who did not enter the court. Seven years old, please thank all the brothers. There are manners to worship the dance, but the emperor is different. Qiu, please surrender to repay your kindness. Ten years in Dali, a gift to a teacher. There are three kings, Wang Deyang county, Jiyang county, Jiyang county, and Xue Guogong, who provide drinks.