Runtime init reload after panic

Some runtimes crash with panics because they assume the environment will self recover, because that's Lambda's behavior when you deploy a function. It'd be very useful if the emulator would initialize the runtime again if the runtime crashed with a panic.

Otherwise, people have to restart the emulator, and it's not very obvious that you have to do that by looking at the logs either.

首先定位 emulator 的 runtime 初始化和 panic 处理路径，然后跟踪崩溃的 runtime 如何在日志中报告。完成的标准是：panic 会使 runtime 重新初始化，而无需重启 emulator，并且相关测试覆盖了这一行为。

由索引模型根据 Issue 内容生成。