使用isPretty后，代码后面多增加了一个逗号;

[zhangdaren]

代码：test({})
$(source).replace("test({$$$})", "var a = {$$$}").root().generate({ isPretty: true })
即可复现，不加 isPretty 是正常的。

复现地址：
https://play.gogocode.io/#code/N4IglgdgDgrgLgYQPYBMCmIBcI5oM5wAUwAvgJQgA0IA7kgE4DWy6WIAZjBAMZxhIQABHHoBDCHnYMAtoXZgANmgCSEKZUGioYDUih8BeMoOAAdIYO6G4ggCSCAvJu0A6AOZIPV9OcGXrgnhIMPTcaI6C8kqqUi5BIWG+ggD0yYKAFOqAm-GAM4mAK-GAe2qABvKA+K6ACEaAIW6Ax3KAgB5J9GhwIUK2hPGhaGQu9VAKomGEpjj4RMC2Y+SDGoMAbqL0mhGj44Od9EhIRJ1uaBBoYrjEgmB4AAr1cHAAnpjC9DDhExAk5lTg0PAAMuJubFdQ+Nx6GB9K8ABaiU7nPh7LDsUQKPBoahWaRQOZoADy8FgcCwInuJCAA

[zhangdaren]

增加一个用例：
https://play.gogocode.io/#code/N4IglgdgDgrgLgYQPYBMCmIBcI4AswDOAdAIYBGAxgBQCUAOhCADQgDuSATgNbLpYgAzGBApwwSCAAI4HEhAIDOAWyoCwAGzQBJCIqaSSUMPqRQxEgjUnAGkyRQtxJAEkkBeA0aIBzJL4fotvaOkgRIMBwUaO6Sapo6ikRhEVFBAPRpkoAU6oCb8YAziYAr8YB7aoAG8oD4roAIRoAhboDHcoCAHkEcaHARUs5UyZFoNERNUOokUVQA5HiEpJS0w-rDDvJOJDEATMM93mgQaLJwaFTAkoQACk1wcACemNIcMNEAvvQQtwzM4NDwADJy3vznUGgEFA4YDML1wJAIx2aYi2WAEJHUBDQLAcSigJCaAHl4LA4FgZDdbkA

[btea]

gogocode-core 的依赖包 recast-yx 产出的代码存在这个问题