Indicate in the WalletError when inputs are locked instead of just throwing InvalidKeychainMask

[marekyggdrasil]

Is your feature request related to a problem? Please describe.

I purposely created a scenario in which all the inputs are locked (but there is sufficient amount in the wallet to perform test tx). Then I run init_send_tx using Owner API and I observe the error I get does not indicate outputs are locked. Instead it says "InvalidKeychainMask" which I think could also be caused by not opening the wallet before calling init_send_tx making it ambiguous.

grinmw.wallet_v3.WalletError: Callng init_send_tx with params {'token': '11e495a841f3e2bba50c02797e0f4bda579be01dbb6bb7b7167f3ba763cf939b', 'args': {'src_acct_name': None, 'amount': 1000000000, 'minimum_confirmations': 10, 'max_outputs': 500, 'num_change_outputs': 1, 'selection_strategy_is_use_all': True, 'target_slate_version': None, 'payment_proof_recipient_address': 'tgrin1l6pv2gzknv8rc29n2cqdqwj8nyq06jwpg36uxeqyqm00l8vuckxqdk9c9s', 'ttl_blocks': None, 'send_args': None}} failed with error code -32099 because: InvalidKeychainMask

( this is a testnet tx )

Describe the solution you'd like

I would like there to be a specific error message that indicates inputs are locked, so that my service can distinguish scenario of not having a wallet opened from the scenario when there are just no available inputs at the moment.

Describe alternatives you've considered

Alternatively I could see it working with different error message when wallet is not opened. As long as they are distinguishable I think it is good.

Additional context

Birds are real!