handle missing suffixes

Signed-off-by: neuronflow <[email protected]>

brainles_preprocessing/registration/eReg/eReg.py

@@ -1,4 +1,6 @@
 # TODO add typing and docs
+import os
+
 from ereg.registration import RegistrationClass
 
 from brainles_preprocessing.registration.registrator import Registrator
@@ -38,6 +40,8 @@ def register(
             configuration_file=self.configuration_file,
         )
 
+        matrix_path = _add_txt_suffix(matrix_path)
+
         registrator.register(
             target_image=fixed_image_path,
             moving_image=moving_image_path,
@@ -69,10 +73,28 @@ def transform(
             configuration_file=self.configuration_file,
         )
 
+        matrix_path = _add_txt_suffix(matrix_path)
+
         registrator.resample_image(
             target_image=fixed_image_path,
             moving_image=moving_image_path,
             output_image=transformed_image_path,
             transform_file=matrix_path,
             log_file=log_file_path,
         )
+
+
+def _add_txt_suffix(filename: str) -> str:
+    """
+    Adds a ".txt" suffix to the filename if it doesn't have any extension.
+
+    Parameters:
+        filename (str): The filename to check and potentially modify.
+
+    Returns:
+        str: The filename with ".txt" suffix added if needed.
+    """
+    base, ext = os.path.splitext(filename)
+    if not ext:
+        filename += ".txt"
+    return filename