Client doesn't check if zero keys exist for acc before sending transaction

[Bargsteen]

Bug Description
Trying to send a transaction from an account which doesn't have any keys does not produce a warning or error.

This error can be triggered by either manually fiddling with the key files or by importing accounts without keys (i.e. malformed backups).

Steps to Reproduce

1. Import valid account A from the mobile wallet
2. Remove all the keys for account A (but not the whole account folder)
   So in /Users/<user>/.config/concordium/accounts:

   ...
   ├── 3mi95ChLEaN8ZhXy1mpY6CMtGyL54YZEYWRcyjbSNPCqGiLvwG
   |   └── encSecretKey.json          // Only file in account `A` folder
   ├── 3mwfniHrUDUPsYDu8TmQvfQVppRoe6UYwJbxTWUMrDexFNigcP
   ...
   

3. Send a transaction with account A: concordium-client transaction send --amount 1 --sender A --receiver B

Expected Result
Account A does not have any keys. Try reimporting the keys again (perhaps making a new mobile export).

Actual Result

Using default energy amount of 401 NRG.
Sending 2000.000000 CCD from '3mi95ChLEaN8ZhXy1mpY6CMtGyL54YZEYWRcyjbSNPCqGiLvwG' ('K3') to '37DWpxKAGAk4BkEoY9uAE8A1KKUSHsrS8HAjVj8uFuyWBNPMyD' ('K1').
Allowing up to 401 NRG to be spent as transaction fee.
Transaction expires on Thu, 19 May 2022 09:50:02 UTC.
Confirm [yN]: y
y
concordium-client: user error (gRPC error: Deserialization error)

Versions

• Software Version: 4.0.3
• OS: macOS

┆Issue is synchronized with this Jira Task by Unito