Remove potential panic from path join (#10012)

Co-authored-by: amtoine <stevan.antoine@gmail.com>

crates/nu-command/src/path/join.rs

@@ -73,9 +73,7 @@ the output of 'path parse' and 'path split' subcommands."#
                 "Input value cannot be joined".to_string(),
                 "value originates from here".into(),
                 head,
-                input
-                    .span()
-                    .expect("non-Empty non-ListStream PipelineData had no span"),
+                input.span().unwrap_or(call.head),
             )),
         }
     }