fix fs move issue on lowest directory

backend/src/lib/outbound/file_system.rs

@@ -336,13 +336,10 @@ impl FileSystem {
 
         let name = {
             let current_path = path.as_str();
-            if let Some(last_slash_index) = current_path.rfind("/")
+            // This unwrap is safe because an `AbsoluteFilePath` always starts with a slash
-                && last_slash_index > 0
+            let last_slash_index = current_path.rfind("/").unwrap();
-            {
+
-                &current_path[last_slash_index + 1..]
+            &current_path[last_slash_index + 1..]
-            } else {
-                return Err(io::ErrorKind::AlreadyExists.into());
-            }
         };
 
         target_path =