From b434a2232036bb32cc5fd3b8f28209f852c4155d Mon Sep 17 00:00:00 2001
From: BLACKBOX Agent <code@blackbox.ai>
Date: Thu, 6 Nov 2025 17:01:15 +0000
Subject: [PATCH] fix(core): handle undefined pull request in update operation

---
 dist/index.js        |  7 +++++++
 src/github-helper.ts | 11 +++++++++++
 2 files changed, 18 insertions(+)

diff --git a/dist/index.js b/dist/index.js
index 75ae3c2f07..c1038cb530 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -1377,6 +1377,13 @@ class GitHubHelper {
             // Update the pull request that exists for this branch and base
             core.info(`Fetching existing pull request`);
             const { data: pulls } = yield this.octokit.rest.pulls.list(Object.assign(Object.assign({}, this.parseRepository(baseRepository)), { state: 'open', head: headBranch, base: inputs.base }));
+            if (pulls.length === 0) {
+                throw new Error(`No open pull request found for head branch '${headBranch}' and base branch '${inputs.base}'. ` +
+                    `This may occur if: (1) the pull request was already merged or closed, ` +
+                    `(2) the token lacks sufficient permissions to list pull requests in this repository, or ` +
+                    `(3) there is an issue with the branch reference format. ` +
+                    `Please verify the pull request exists and the token has 'pull-requests: read' permission.`);
+            }
             core.info(`Attempting update of pull request`);
             const { data: pull } = yield this.octokit.rest.pulls.update(Object.assign(Object.assign({}, this.parseRepository(baseRepository)), { pull_number: pulls[0].number, title: inputs.title, body: inputs.body }));
             core.info(`Updated pull request #${pull.number} (${headBranch} => ${inputs.base})`);
diff --git a/src/github-helper.ts b/src/github-helper.ts
index 6d41e06d72..e60c56b2be 100644
--- a/src/github-helper.ts
+++ b/src/github-helper.ts
@@ -119,6 +119,17 @@ export class GitHubHelper {
       head: headBranch,
       base: inputs.base
     })
+
+    if (pulls.length === 0) {
+      throw new Error(
+        `No open pull request found for head branch '${headBranch}' and base branch '${inputs.base}'. ` +
+          `This may occur if: (1) the pull request was already merged or closed, ` +
+          `(2) the token lacks sufficient permissions to list pull requests in this repository, or ` +
+          `(3) there is an issue with the branch reference format. ` +
+          `Please verify the pull request exists and the token has 'pull-requests: read' permission.`
+      )
+    }
+
     core.info(`Attempting update of pull request`)
     const {data: pull} = await this.octokit.rest.pulls.update({
       ...this.parseRepository(baseRepository),