fix default text for populate method

ogs6py/_version.py

@@ -1,3 +1,3 @@
 # -*- coding: utf-8 -*-
 """Provide a central version."""
-__version__ = "0.401"
+__version__ = "0.402"

ogs6py/classes/build_tree.py

@@ -30,7 +30,7 @@ def _convertargs(cls, args):
                 args[item] = str(value)
 
     @classmethod
-    def populate_tree(cls, parent, tag, text='', attr=None, overwrite=False):
+    def populate_tree(cls, parent, tag, text=None, attr=None, overwrite=False):
         """
         method to create dictionary from an xml entity
         """

ogs6py/classes/mesh.py

@@ -40,7 +40,7 @@ def add_mesh(self, filename, axially_symmetric=None):
         elif isinstance(axially_symmetric, str):
             attr_dict = {"axially_symmetric": axially_symmetric}
         if self.mesh is not None:
-            if self.mesh.text == "":
+            if self.mesh.text == "" or self.mesh.text is None:
                 self.populate_tree(self.root, "mesh", text=filename, attr=attr_dict, overwrite=True)
             else:
                 entry = self.mesh.text

ogs6py/ogs.py

@@ -151,6 +151,8 @@ def _remove_empty_elements(self):
             entry = root.find(element)
             if entry is not None:
                 self.remove_element(".", tag=entry.tag, text="")
+            if entry is not None:
+                self.remove_element(".", tag=entry.tag, text=None)
         for element in empty_el_list:
             entry = root.find(element)
             if entry is not None: