fix: commentBody may be null (#706)

* fix: `commentBody` may be `null`

This handles the cases where `pull_request_review` events have no
comments (`commentBody` field is `null`). In those cases, the `null`
value is converted to the empty string.

The issue was testing `!commentBody` which was triggerring on empty
strings as well. This guard was removed (which is the fix), but for
clarity, the `commentBody` field was also made optional to make it clear
that the comment may be missing.

* fix: bun run format

src/create-prompt/index.ts

@@ -192,11 +192,6 @@ export function prepareContext(
       if (!isPR) {
         throw new Error("IS_PR must be true for pull_request_review event");
       }
-      if (!commentBody) {
-        throw new Error(
-          "COMMENT_BODY is required for pull_request_review event",
-        );
-      }
       eventData = {
         eventName: "pull_request_review",
         isPR: true,

src/create-prompt/types.ts

@@ -23,7 +23,7 @@ type PullRequestReviewEvent = {
   eventName: "pull_request_review";
   isPR: true;
   prNumber: string;
-  commentBody: string;
+  commentBody?: string; // May be absent for approvals without comments
   claudeBranch?: string;
   baseBranch?: string;
 };