Fix file-scoped comment failing with "Error: File has been deleted"

When creating a file-scoped comment (range is undefined), the
createReviewThread method was passing `line: 0` to the GitHub GraphQL
API. The API does not accept line 0 and returns a null thread, which
caused the misleading "File has been deleted" error.

Fix: pass endLine directly (undefined for file-scoped comments) instead
of converting undefined to 0. The line parameter is not required when
subjectType is FILE.

Agent-Logs-Url: https://github.com/microsoft/vscode-pull-request-github/sessions/2e5f5355-cccd-4ac6-b866-9d00dcd8b8b4

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

Author: Copilot

src/github/pullRequestModel.ts

@@ -751,7 +751,7 @@ export class PullRequestModel extends IssueModel<PullRequest> implements IPullRe
 					pullRequestId: this.graphNodeId,
 					pullRequestReviewId: pendingReviewId,
 					startLine: startLine === endLine ? undefined : startLine,
-					line: (endLine === undefined) ? 0 : endLine,
+					line: endLine,
 					side,
 					subjectType: (startLine === undefined || endLine === undefined) ? SubjectType.FILE : SubjectType.LINE
 				}

src/test/view/reviewCommentController.test.ts

@@ -339,5 +339,106 @@ describe('ReviewCommentController', function () {
 			assert.strictEqual(Object.keys(workspaceFileChangeCommentThreads)[0], fileName);
 			assert.strictEqual(workspaceFileChangeCommentThreads[fileName].length, 1);
 		});
+
+		it('creates a file-scoped comment on an empty thread', async function () {
+			const fileName = 'data/products.json';
+			const uri = vscode.Uri.parse(`${repository.rootUri.toString()}/${fileName}`);
+			await activePullRequest.initializeReviewThreadCache();
+			const localFileChanges = [createLocalFileChange(uri, fileName, repository.rootUri)];
+			const reviewModel = new ReviewModel();
+			reviewModel.localFileChanges = localFileChanges;
+			const reviewCommentController = new TestReviewCommentController(
+				reviewManager,
+				manager,
+				repository,
+				reviewModel,
+				gitApiImpl,
+				telemetry
+			);
+			const thread = createGHPRCommentThread('review-1.2', uri);
+			thread.range = undefined as any;
+
+			sinon.stub(activePullRequest, 'validateDraftMode').returns(Promise.resolve(false));
+			sinon.stub(activePullRequest, 'getReviewThreads').returns(Promise.resolve([]));
+			sinon.stub(activePullRequest, 'getPendingReviewId').returns(Promise.resolve(undefined));
+
+			sinon.stub(manager, 'getCurrentUser').returns(Promise.resolve({
+				login: 'rmacfarlane',
+				url: 'https://github.com/rmacfarlane',
+				id: '123',
+				accountType: AccountType.User
+			}));
+
+			sinon.stub(vscode.workspace, 'getWorkspaceFolder').returns({
+				uri: repository.rootUri,
+				name: '',
+				index: 0,
+			});
+
+			sinon.stub(vscode.workspace, 'asRelativePath').callsFake((pathOrUri: string | vscode.Uri): string => {
+				const path = pathOrUri.toString();
+				return path.substring('/root/'.length);
+			});
+
+			sinon.stub(repository, 'diffWith').returns(Promise.resolve(''));
+
+			await reviewCommentController.initialize();
+
+			githubRepo.queryProvider.expectGraphQLMutation(
+				{
+					mutation: schema.AddReviewThread,
+					variables: {
+						input: {
+							path: fileName,
+							body: 'file comment',
+							pullRequestId: activePullRequest.graphNodeId,
+							pullRequestReviewId: undefined,
+							startLine: undefined,
+							line: undefined,
+							side: 'RIGHT',
+							subjectType: 'FILE'
+						}
+					}
+				},
+				{
+					data: {
+						addPullRequestReviewThread: {
+							thread: {
+								id: 2,
+								isResolved: false,
+								viewCanResolve: true,
+								path: fileName,
+								line: null,
+								startLine: null,
+								originalStartLine: null,
+								originalLine: null,
+								diffSide: 'RIGHT',
+								isOutdated: false,
+								subjectType: 'FILE',
+								comments: {
+									nodes: [
+										{
+											databaseId: 2,
+											id: 2,
+											body: 'file comment',
+											commit: {},
+											diffHunk: '',
+											reactionGroups: [],
+											author: {}
+										}
+									]
+								}
+							}
+						}
+					}
+				}
+			)
+
+			const newReviewThreadPromise = asPromise(activePullRequest.onDidChangeReviewThreads);
+			await reviewCommentController.createOrReplyComment(thread, 'file comment', false);
+			await newReviewThreadPromise;
+			assert.strictEqual(thread.comments.length, 1);
+			assert.strictEqual(thread.comments[0].parent, thread);
+		});
 	});
 });