fix: Fix comparison in Docker under random UID

Dockerfile

@@ -39,8 +39,6 @@ EXPOSE 8000
 
 COPY ./templates /views
 
-# Cache directory has to be writable
-RUN chmod -R 777 /home
 ENV HOME=/home
 
 COPY entrypoint.sh /entrypoint.sh
@@ -53,10 +51,11 @@ ENV MODE=production
 COPY frontend/fetch-version.py ./frontend/
 RUN python frontend/fetch-version.py
 
-# Run as non-root user per default
-USER 1000
-
 # Pre-install npm dependencies for context diagrams
 RUN python -c "from capellambse_context_diagrams import _elkjs; _elkjs._install_required_npm_pkg_versions()"
 
+# Run as non-root user per default
+RUN chmod -R 777 /home
+USER 1000
+
 ENTRYPOINT ["/entrypoint.sh"]

capella_model_explorer/backend/explorer.py

@@ -296,6 +296,7 @@ async def post_compare(commit_range: CommitRange):
                 self.diff["lookup"] = create_diff_lookup(self.diff["objects"])
                 return {"success": True}
             except Exception as e:
+                LOGGER.exception("Failed to compare versions")
                 return {"success": False, "error": str(e)}
 
         @self.router.post("/api/object-diff")
@@ -375,5 +376,5 @@ def create_diff_lookup(data, lookup=None):
                     if obj["children"]:
                         create_diff_lookup(obj["children"], lookup)
     except Exception:
-        pass
+        LOGGER.exception("Cannot create diff lookup")
     return lookup

capella_model_explorer/backend/model_diff.py

@@ -267,7 +267,7 @@ def compare_objects(
             "attributes": attributes,
             "children": children,
         }
-    return None
+    return {}
 
 
 def _handle_attribute_property(attr, old_object, new_object, attributes):

frontend/src/views/ModelComparisonView.jsx

@@ -113,7 +113,7 @@ export const ModelComparisonView = ({ endpoint }) => {
             modelDiff.objects &&
             Object.keys(modelDiff.objects).map(
               (layer) =>
-                modelDiff.objects[layer] && (
+                Object.keys(modelDiff.objects[layer]).length > 0 && (
                   <DiffExplorer
                     node={modelDiff.objects[layer]}
                     setObjectID={setObjectID}