Never panic based on remote-provided inputs

[tnull]

Describe the bug
I just hit a panic in bdk_esplora as I misconfigured the URL for the Esplora endpoint to a server on a different network (i.e., left it untouched when switching networks from mainnet to signet). This results in in hitting this expect:

https://github.com/bitcoindevkit/bdk/blob/88330f603cb415d01c88f1a579f20a21cb8c1658/crates/esplora/src/async_ext.rs#L240

While this is just a minor inconvenience, it surfaces a much larger problem: from a quick look, there are many cases of expect and unwrap in the chain-syncing crates (i.e., bdk_esplora,bdk_electrum), and at least a few of them seem to be directly or indirectly based on remote-provided inputs that aren't validated otherwise.

This should never happen, essentially crates dealing with remote-provided data should never expect or unwrap. Given that all of these methods return Result<.., Error> there really is no reason why they couldn't just return errors in these cases.

To Reproduce
For example, switch networks without switching Esplora URLs.

Expected behavior
Never panic based on remote-provided inputs

[oleonardolima]

Yes, that's also not an exclusive problem for bdk-esplora, bdk-electrum can also suffer from similar issues.

It can be solved or minimized by relying on errors from the client library and/or refatoring the code to defensively implements library logic, instead of using expects and panics, previous related issue: bitcoindevkit/bdk#1696

[tnull]

@notmandatory can we reopen this issue, as it doesn't seem resolved?: bitcoindevkit/bdk-ffi#863

[reez]

@notmandatory can we reopen this issue, as it doesn't seem resolved?: bitcoindevkit/bdk-ffi#863

+1

I ran into this issue with bdk-ffi and a mobile app.

I opened up a PR on bdk-ffi to address it there bitcoindevkit/bdk-ffi#863

But was also thinking ultimately the solution was best if it was done on bdk_esplora

[reez]

And just to add some additional commentary, I see there was this bitcoindevkit/bdk#1971 PR that addressed an esplora panic which is good, the panic I ran into is basically right under that related to "evicted are in order" .expect("evicted are in order");