feat: More error handling

capella_model_explorer/backend/explorer.py

@@ -288,7 +288,7 @@ async def post_compare(commit_range: CommitRange):
                 self.diff["lookup"] = create_diff_lookup(self.diff["objects"])
                 if self.diff["lookup"]:
                     return {"success": True}
-                return {"success": False, "error": "No diff data available"}
+                return {"success": False, "error": "No model changes to show"}
             except Exception as e:
                 LOGGER.exception("Failed to compare versions")
                 return {"success": False, "error": str(e)}
@@ -303,8 +303,11 @@ async def post_object_diff(object_id: ObjectDiffID):
 
         @self.router.get("/api/commits")
         async def get_commits():
-            result = model_diff.populate_commits(self.model)
-            return result
+            try:
+                result = model_diff.populate_commits(self.model)
+                return result
+            except Exception as e:
+                return {"error": str(e)}
 
         @self.router.get("/api/diff")
         async def get_diff():

capella_model_explorer/backend/model_diff.py

@@ -168,7 +168,7 @@ def _get_revision_info(
         .strip()
         .split("\x00")
     )
-    subject = description.splitlines()[0]
+    subject = description.splitlines()[0] if description.splitlines() else ""
     try:
         tag = subprocess.check_output(
             ["git", "tag", "--points-at", revision],

frontend/src/components/ModelDiff.jsx

@@ -87,15 +87,18 @@ export const ModelDiff = ({ onRefetch, hasDiffed }) => {
 
       const response = await fetch(`${API_BASE_URL}/commits`);
 
-      if (!response.ok) throw new Error('Failed to fetch commits info.');
+      if (!response.ok) {
+        const err = await response.json();
+        throw new Error(err.error || 'Internal server error.');
+      }
 
       const data = await response.json();
       if (data === null) {
-        alert('Not a git repo');
-        return;
+        throw new Error('Not a git repo');
       } else if (data.length < 2) {
-        alert('Not enough commits to compare.');
-        return;
+        throw new Error('Not enough commits to compare.');
+      } else if (data.error) {
+        throw new Error('Internal server error: ' + data.error);
       }
 
       setCommitDetails(data);
@@ -110,7 +113,7 @@ export const ModelDiff = ({ onRefetch, hasDiffed }) => {
       setSelectionOptions(options);
       setIsPopupVisible(true);
     } catch (err) {
-      setError(err.message);
+      alert(err.message || 'An error occurred while fetching commits.');
     }
   };
 
@@ -212,8 +215,7 @@ export const ModelDiff = ({ onRefetch, hasDiffed }) => {
                       <div
                         className="mt-4 rounded border border-green-400
                           bg-green-100 p-4 text-green-700">
-                        <strong>Success:</strong> Successfully compared
-                        versions ✓
+                        Successfully compared versions ✓
                       </div>
                       <button
                         className="mt-4 rounded bg-green-500 px-4 py-2
@@ -237,9 +239,15 @@ export const ModelDiff = ({ onRefetch, hasDiffed }) => {
                   {loadingState === 'error' && (
                     <>
                       <div
-                        className="mt-4 rounded border border-red-400
-                          bg-red-100 p-4 text-red-700">
-                        <strong>Error:</strong> {error}
+                        className={`mt-4 rounded border p-4 ${
+                        error === 'No model changes to show'
+                            ? 'border-yellow-400 bg-yellow-100 text-yellow-700'
+                            : 'border-red-400 bg-red-100 text-red-700'
+                        }`}>
+                        {error !== 'No model changes to show' && (
+                          <strong>Error:</strong>
+                        )}{' '}
+                        {error}
                       </div>
                       <button
                         className="mt-4 rounded bg-custom-blue px-4 py-2