This took me a while to hunt down.

We ended up mis-configuring our access_key param for azure blob and this was the error:

Unexpected (persistent) at stat, context: { called: reqsign::Sign, service: azblob, path: index.msgpack } => signing http request, source: base64 decode failed for InvalidByte(85, 61): base64 decode failed for InvalidByte(85, 61)

I've traced this back to the pub async fn sign<T>(&self, req: &mut Request<T>) -> Result<()> { function in core/src/services/azblob/core.rs.

The error I'd expect to read something like:

bad `access_key` configured, could not decode as base-64

Ideally it would be helpful to report the error sooner, say in:

impl Builder for AzblobBuilder {
    fn build(&mut self) -> Result<Self::Accessor> {

Related... I've also noticed separately that building the operator from a map can panic if the map doesn't contain the right keys (e.g. if container is missing).

This is because of this code:

    fn from_map(map: HashMap<String, String>) -> Self {
        let config = AzblobConfig::deserialize(ConfigDeserializer::new(map))
            .expect("config deserialize must **succeed");**

These issues would be a small PR to raise, but I appreciate that with so many service implementations there's probably a "proper" way of doing this in the context of opendal.