Update swmmanywhere/preprocessing.py

Co-authored-by: Diego Alonso Álvarez <6095790+dalonsoa@users.noreply.github.com>

swmmanywhere/preprocessing.py

@@ -32,8 +32,7 @@ def next_directory(keyword: str, directory: Path) -> int:
         int: Next directory number.
     """
     existing_dirs = [int(d.name.split("_")[-1]) for d in directory.glob(f"{keyword}_*"))]
-    next_dir_number = 1 if not existing_dirs else max(existing_dirs) + 1
-    return next_dir_number
+    return 1 if not existing_dirs else max(existing_dirs) + 1
 
 def check_bboxes(bbox: tuple[float, float, float, float],
                  data_dir: Path) -> int | bool: