feat: Improve upload error message to show cause

src/commands/build/upload.rs

@@ -325,7 +325,13 @@ pub fn execute(matches: &ArgMatches) -> Result<()> {
             }
         );
         for (path, reason) in errored_paths_and_reasons {
-            warn!("  - {} ({})", path.display(), reason);
+            warn!("  - {}", path.display());
+            if let Some(source) = reason.source() {
+                warn!("    Error: {}", reason);
+                warn!("    Cause: {}", source);
+            } else {
+                warn!("    Error: {}", reason);
+            }
         }
     }