unexpected_http_status_code can panic b/c using unwrap

[hseeberger]

response
    .text()
    .await
    .map_err(|e| format!("Failed to get response body as text: {e}"))
    .and_then(|text| {
        serde_json::from_str::<Value>(&text)
            .map(|v| v["error"]["message"].to_string())
            .map_err(|e| format!("Failed to parse error response: {e}"))
    })
    .unwrap(),

(https://github.com/hseeberger/pub-sub-client/blob/main/pub-sub-client/src/error/mod.rs#L41)

If either text().await or serde_json::from_str returns an Err, unwrap will panic.

[hseeberger]

The above code should produce a String thereby never panicking. The map_err calls already convert any error into a String, therefore we should use .unwrap_or_else(identity) instead of .unwrap.

[hseeberger]

Closed via #12.