Call to ‘set-and-coerce-property!’ has too few arguments (3; must be 4)

App Inventor 2

编译apk，报错：Call to ‘set-and-coerce-property!’ has too few arguments (3; must be 4)


原因是因为代码块有问题/报错，有空的地方没有填值，比如这种：


参考：https://community.appinventor.mi ... 3-must-be-4/20690/4