Fixed error during building schedule from ods

We were discarding some styles that didn't have any style properties and then we always needed to keep it in mind later on, now we just create empty dict for those.

src/blenderbim/blenderbim/bim/module/drawing/scheduler.py

@@ -42,16 +42,18 @@ class Scheduler:
         styles = {}
         for style in doc.getElementsByType(Style):
             name = style.getAttribute("name")
-            # looking for table-column-properties or table-row-properties
+            styles[name] = {}
+
+            # NOTE: there are also styles that inherit from parent styles that we do not process atm
             if not style.firstChild:
                 continue
+
             if style.firstChild.tagName in ["style:table-column-properties", "style:table-row-properties"]:
                 style_children = [style.firstChild]
             else:
                 # for style:table-cell-properties we need to collect also text and paragraph properties
                 style_children = style.childNodes
 
-            styles[name] = {}
             for child in style_children:
                 child_params = {key[1]: value for key, value in child.attributes.items()}
                 styles[name].update(child_params)