Grin: Double spend shouldn't result in panic

[Makadu59]

following the discussion on 504, we fil a new issue

The steps :

• i have get a .json file named mimbelus.json and run the following command :
  grin wallet -p password receive --input mimbelus.json
• the tx was mined on block 17261
• I runned the same command on an other node with the same mimbelous.json
• I get the following panic https://pastebin.com/E7HNwkUn

@ignopeverell answers :
"In this case it sounds like something going wring is normal, you're trying to spend twice the same inputs, if I'm understanding correctly. Is that right?

However a crash is definitely not the best way to handle this, we should report it with a more user-friendly message like "funds already spent"."

[ignopeverell]

This should be trivial to fix but ties up to the API not returning great errors (ends up as a 500).

[Makadu59]

It was fast !! 🥇
:)

[mably]

It looks like the rejected output is still added to the wallet (unconfirmed), after a few double spend attempts on my side:

https://i.imgur.com/bdLdJY5.png

But the wallet doesn't crash anymore 👍

[ignopeverell]

That's a different fix :-) Going to look at that next.

[ignopeverell]

Should be fixed as well now.

[mably]

Things are improving fast, thanks @ignopeverell 😄