Fixed error message when wrong paths are given to evaluation.

src/robofish/io/io.py

@@ -49,6 +49,10 @@ def read_multiple_files(
 
     sf_dict = {}
     for path in paths:
+        assert (
+            path is not None and path.exists()
+        ), f"Path does not exists {path.resolve()}."
+
         if path.is_dir():
             logging.info("found dir %s" % path)
             # Find all hdf5 files in folder
@@ -65,9 +69,12 @@ def read_multiple_files(
                 )
                 if max_files is not None and len(sf_dict) >= max_files:
                     break
-        elif path is not None and path.exists():
+        else:
             logging.info("found file %s" % path)
             sf_dict[path] = robofish.io.File(path=path, strict_validate=strict_validate)
+
+    assert len(sf_dict) > 0, f"No files found in given Paths. {paths}"
+
     return sf_dict