cli: add error cause for TCP server's app_loop

If there is an error when running as a TCP server (for instance
a fatal formatting error on the stream), then the CLI will log
the error, close the connection and continue listening for more
TCP connections. This adds the cause of the error to the log,
using Anyhow's Error alternate formatting.

Signed-off-by: Daniel Estévez <[email protected]>

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 
 - Do not fail if a packet cannot be written to the TUN.
+- Add cause when logging errors for the TCP server.
 
 ## [0.4.1] - 2023-09-29
 

src/cli.rs

@@ -200,7 +200,7 @@ pub fn main() -> Result<()> {
                 }
                 app.bbframe_recv = Some(BBFrameStream::new(stream));
                 if let Err(err) = app.app_loop() {
-                    log::error!("error; waiting for another client: {err}");
+                    log::error!("error; waiting for another client: {err:#}");
                 }
             }
         }