[nxtomomill.utils][__insert_in_vds] handle use case when data_frm_url is 2D instead of 3D

nxtomomill/utils.py

@@ -612,7 +612,13 @@ class _FrameAppender:
                 self.__insert_in_vds(h5s, url, data_frm_url)
 
     def __insert_in_vds(self, h5s, url, data_frm_url):
-        n_frames, dim_2, dim_1 = data_frm_url.shape
+        if data_frm_url.ndim == 2:
+            n_frames = 1
+            dim_2, dim_1 = data_frm_url.shape
+        elif data_frm_url.ndim == 3:
+            n_frames, dim_2, dim_1 = data_frm_url.shape
+        else:
+            raise ValueError("data to had is expected to be 2 or 3 d")
 
         virtual_sources_len = []
         virtual_sources = []