Fix exit code

[va-an]

Fix for #170.

I think this is the simplest way to do it.
It's also possible to change the main signature to return Result, which should provide similar behavior, but this option isn't compatible with the #[maybe_async] macro, so I decided not to complicate things.

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR

[tvpeter]

@va-an, could you please rebase and confirm if the issue still exists; otherwise close the PR. Thank you for your efforts.

[va-an]

@va-an, could you please rebase and confirm if the issue still exists; otherwise close the PR. Thank you for your efforts.

I've replied in #170.
Let's discuss there.

[va-an]

@tvpeter, rebased to master.
I composed a command as close as possible to the one in the original issue in order to reproduce the behavior.

From master - exit code 0:

-> % cargo run --features electrum -- \
    --network signet \
    wallet \
    --int-descriptor "" \
    --client-type electrum \
    --database-type sqlite \
    --url some \
    new_address
[2025-04-18T14:31:56Z ERROR bdk_cli] Generic error: An external descriptor is required.
-> % echo $?
0

With fix - exit code 1:

-> % cargo run --features electrum -- \
    --network signet \
    wallet \
    --int-descriptor "" \
    --client-type electrum \
    --database-type sqlite \
    --url some \
    new_address
[2025-04-18T14:31:19Z ERROR bdk_cli] Generic error: An external descriptor is required.
-> % echo $?
1

[va-an]

Please let me know what I can do to make this PR ready to merge.
In the meantime, I'll continue studying the bdk source code to be able to make more significant changes in the future.

[va-an]

Made a force-push to sign my commit.

[notmandatory]

ACK 04c7f88

[tvpeter]

@va-an please rebase.

[va-an]

@va-an please rebase.

Done! I also added a checklist to the description.

[coveralls]

Pull Request Test Coverage Report for Build 15389199914

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 2 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.003%) to 2.7%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/main.rs	0	2	0.0%

Totals
Change from base Build 15127343813:	-0.003%
Covered Lines:	25
Relevant Lines:	926

---

💛 - Coveralls