Add support for stderr and exit code (#4647)

crates/nu-command/src/conversions/into/binary.rs

@@ -99,7 +99,7 @@ fn into_binary(
     let column_paths: Vec<CellPath> = call.rest(engine_state, stack, 0)?;
 
     match input {
-        PipelineData::RawStream(stream, ..) => {
+        PipelineData::ExternalStream { stdout: stream, .. } => {
             // TODO: in the future, we may want this to stream out, converting each to bytes
             let output = stream.into_bytes()?;
             Ok(Value::Binary {