Apply suggestions from code review of branch download-stitched-image

Co-authored-by: Beth Probert <beth_probert@outlook.com>

src/openflexure_microscope_server/scan_directories.py

@@ -73,7 +73,7 @@ class ScanDirectoryManager:
     def get_file_path_from(
         self, scan_name: str, filename: str, check_exists: bool = False
     ) -> Optional[str]:
-        """Return the file full path for the file within a scan directory
+        """Return the full file path for the file within a scan directory
 
         If check_exists is True then None will be returned if the file does
         not exist.

tests/test_scan_directories.py

@@ -356,7 +356,7 @@ def test_all_files():
     all_files = scan_dir.all_files()
 
     # As standard for 8 layers there are 89 jpegs and 1 dzi file.
-    assert len(all_files) == 90
+    assert len(set(all_files)) == 90
     dzi_file = None
     # Check all files exist
     for file in all_files: