吴狗蛋

always exit with exit code 0 is unfriendly to other external programs. we need to exit with a non-0 exit code when the result is failure.

avoid ID field overflow when use some WebSocket RPC.  

if not, the reward in log, `bus.theoretical_rewards` and `proof.total_rewards` will be incorrect.

fix: min difficulty

11

According to https://github.com/regolith-labs/ore/blob/b4bae9c823444db86fbc7f08aa624690a9d33e6b/program/src/mine.rs#L93 , the difficulty minted can equal to min difficulty.