Adding guard checks.

out/github-action.cjs

@@ -93626,11 +93626,11 @@ async function getCommitDiff(commitSha) {
       );
       const diff2 = response.data ?? "";
       if (!diff2) {
-        core.warning(`No diff data for commit ${commitSha}`);
+        core.warning(`\u26A0\uFE0F  No diff returned for commit ${commitSha}`);
       }
       return { sha: commitSha, diff: diff2 };
     } catch (error2) {
-      core.error(`Error fetching Gitea/Forgejo diff for ${commitSha}: ${error2}`);
+      core.error(`Failed to fetch Gitea/Forgejo commit diff for ${commitSha}: ${error2}`);
       throw error2;
     }
   }
@@ -93640,12 +93640,14 @@ async function getCommitDiff(commitSha) {
       owner,
       repo,
       ref: commitSha,
-      headers: { Accept: "application/vnd.github.v3.diff" }
+      headers: {
+        Accept: "application/vnd.github.v3.diff"
+      }
     }
   );
   const diff = diffResponse.data ?? "";
   if (!diff) {
-    core.warning(`No diff data from GitHub for commit ${commitSha}`);
+    core.warning(`\u26A0\uFE0F  No diff returned from GitHub for commit ${commitSha}`);
   }
   return { sha: commitSha, diff };
 }
@@ -93715,7 +93717,14 @@ async function improveCommitMessages(commitsToImprove) {
   const commitSHAsToImprove = filteredCommits.map((commit) => commit.id);
   const diffsWithSHAs = await getDiffsBySHAs(commitSHAsToImprove);
   ce("Done.");
-  const improvedMessagesWithSHAs = await improveMessagesInChunks(diffsWithSHAs);
+  const validDiffsWithSHAs = diffsWithSHAs.filter(
+    (item) => typeof item.diff === "string" && item.diff.length > 0
+  );
+  if (validDiffsWithSHAs.length === 0) {
+    ce("No valid diffs received; skipping improvement step.");
+    return;
+  }
+  const improvedMessagesWithSHAs = await improveMessagesInChunks(validDiffsWithSHAs);
   console.log(
     `Improved ${improvedMessagesWithSHAs.length} commit messages`
   );