I think this works better

src/git.d.ts

@@ -0,0 +1,259 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { Uri, SourceControlInputBox, Event, CancellationToken } from 'vscode';
+
+export interface Git {
+	readonly path: string;
+}
+
+export interface InputBox {
+	value: string;
+}
+
+export const enum RefType {
+	Head,
+	RemoteHead,
+	Tag
+}
+
+export interface Ref {
+	readonly type: RefType;
+	readonly name?: string;
+	readonly commit?: string;
+	readonly remote?: string;
+}
+
+export interface UpstreamRef {
+	readonly remote: string;
+	readonly name: string;
+}
+
+export interface Branch extends Ref {
+	readonly upstream?: UpstreamRef;
+	readonly ahead?: number;
+	readonly behind?: number;
+}
+
+export interface Commit {
+	readonly hash: string;
+	readonly message: string;
+	readonly parents: string[];
+	readonly authorDate?: Date;
+	readonly authorName?: string;
+	readonly authorEmail?: string;
+	readonly commitDate?: Date;
+}
+
+export interface Submodule {
+	readonly name: string;
+	readonly path: string;
+	readonly url: string;
+}
+
+export interface Remote {
+	readonly name: string;
+	readonly fetchUrl?: string;
+	readonly pushUrl?: string;
+	readonly isReadOnly: boolean;
+}
+
+export const enum Status {
+	INDEX_MODIFIED,
+	INDEX_ADDED,
+	INDEX_DELETED,
+	INDEX_RENAMED,
+	INDEX_COPIED,
+
+	MODIFIED,
+	DELETED,
+	UNTRACKED,
+	IGNORED,
+	INTENT_TO_ADD,
+
+	ADDED_BY_US,
+	ADDED_BY_THEM,
+	DELETED_BY_US,
+	DELETED_BY_THEM,
+	BOTH_ADDED,
+	BOTH_DELETED,
+	BOTH_MODIFIED
+}
+
+export interface Change {
+
+	/**
+	 * Returns either `originalUri` or `renameUri`, depending
+	 * on whether this change is a rename change. When
+	 * in doubt always use `uri` over the other two alternatives.
+	 */
+	readonly uri: Uri;
+	readonly originalUri: Uri;
+	readonly renameUri: Uri | undefined;
+	readonly status: Status;
+}
+
+export interface RepositoryState {
+	readonly HEAD: Branch | undefined;
+	readonly refs: Ref[];
+	readonly remotes: Remote[];
+	readonly submodules: Submodule[];
+	readonly rebaseCommit: Commit | undefined;
+
+	readonly mergeChanges: Change[];
+	readonly indexChanges: Change[];
+	readonly workingTreeChanges: Change[];
+
+	readonly onDidChange: Event<void>;
+}
+
+export interface RepositoryUIState {
+	readonly selected: boolean;
+	readonly onDidChange: Event<void>;
+}
+
+/**
+ * Log options.
+ */
+export interface LogOptions {
+	/** Max number of log entries to retrieve. If not specified, the default is 32. */
+	readonly maxEntries?: number;
+}
+
+export interface CommitOptions {
+	all?: boolean | 'tracked';
+	amend?: boolean;
+	signoff?: boolean;
+	signCommit?: boolean;
+	empty?: boolean;
+}
+
+export interface Repository {
+
+	readonly rootUri: Uri;
+	readonly inputBox: InputBox;
+	readonly state: RepositoryState;
+	readonly ui: RepositoryUIState;
+
+	getConfigs(): Promise<{ key: string; value: string; }[]>;
+	getConfig(key: string): Promise<string>;
+	setConfig(key: string, value: string): Promise<string>;
+	getGlobalConfig(key: string): Promise<string>;
+
+	getObjectDetails(treeish: string, path: string): Promise<{ mode: string, object: string, size: number }>;
+	detectObjectType(object: string): Promise<{ mimetype: string, encoding?: string }>;
+	buffer(ref: string, path: string): Promise<Buffer>;
+	show(ref: string, path: string): Promise<string>;
+	getCommit(ref: string): Promise<Commit>;
+
+	clean(paths: string[]): Promise<void>;
+
+	apply(patch: string, reverse?: boolean): Promise<void>;
+	diff(cached?: boolean): Promise<string>;
+	diffWithHEAD(): Promise<Change[]>;
+	diffWithHEAD(path: string): Promise<string>;
+	diffWith(ref: string): Promise<Change[]>;
+	diffWith(ref: string, path: string): Promise<string>;
+	diffIndexWithHEAD(): Promise<Change[]>;
+	diffIndexWithHEAD(path: string): Promise<string>;
+	diffIndexWith(ref: string): Promise<Change[]>;
+	diffIndexWith(ref: string, path: string): Promise<string>;
+	diffBlobs(object1: string, object2: string): Promise<string>;
+	diffBetween(ref1: string, ref2: string): Promise<Change[]>;
+	diffBetween(ref1: string, ref2: string, path: string): Promise<string>;
+
+	hashObject(data: string): Promise<string>;
+
+	createBranch(name: string, checkout: boolean, ref?: string): Promise<void>;
+	deleteBranch(name: string, force?: boolean): Promise<void>;
+	getBranch(name: string): Promise<Branch>;
+	setBranchUpstream(name: string, upstream: string): Promise<void>;
+
+	getMergeBase(ref1: string, ref2: string): Promise<string>;
+
+	status(): Promise<void>;
+	checkout(treeish: string): Promise<void>;
+
+	addRemote(name: string, url: string): Promise<void>;
+	removeRemote(name: string): Promise<void>;
+
+	fetch(remote?: string, ref?: string, depth?: number): Promise<void>;
+	pull(unshallow?: boolean): Promise<void>;
+	push(remoteName?: string, branchName?: string, setUpstream?: boolean): Promise<void>;
+
+	blame(path: string): Promise<string>;
+	log(options?: LogOptions): Promise<Commit[]>;
+
+	commit(message: string, opts?: CommitOptions): Promise<void>;
+}
+
+export type APIState = 'uninitialized' | 'initialized';
+
+export interface API {
+	readonly state: APIState;
+	readonly onDidChangeState: Event<APIState>;
+	readonly git: Git;
+	readonly repositories: Repository[];
+	readonly onDidOpenRepository: Event<Repository>;
+	readonly onDidCloseRepository: Event<Repository>;
+
+	toGitUri(uri: Uri, ref: string): Uri;
+	getRepository(uri: Uri): Repository | null;
+}
+
+export interface GitExtension {
+
+	readonly enabled: boolean;
+	readonly onDidChangeEnablement: Event<boolean>;
+
+	/**
+	 * Returns a specific API version.
+	 *
+	 * Throws error if git extension is disabled. You can listed to the
+	 * [GitExtension.onDidChangeEnablement](#GitExtension.onDidChangeEnablement) event
+	 * to know when the extension becomes enabled/disabled.
+	 *
+	 * @param version Version number.
+	 * @returns API instance
+	 */
+	getAPI(version: 1): API;
+}
+
+export const enum GitErrorCodes {
+	BadConfigFile = 'BadConfigFile',
+	AuthenticationFailed = 'AuthenticationFailed',
+	NoUserNameConfigured = 'NoUserNameConfigured',
+	NoUserEmailConfigured = 'NoUserEmailConfigured',
+	NoRemoteRepositorySpecified = 'NoRemoteRepositorySpecified',
+	NotAGitRepository = 'NotAGitRepository',
+	NotAtRepositoryRoot = 'NotAtRepositoryRoot',
+	Conflict = 'Conflict',
+	StashConflict = 'StashConflict',
+	UnmergedChanges = 'UnmergedChanges',
+	PushRejected = 'PushRejected',
+	RemoteConnectionError = 'RemoteConnectionError',
+	DirtyWorkTree = 'DirtyWorkTree',
+	CantOpenResource = 'CantOpenResource',
+	GitNotFound = 'GitNotFound',
+	CantCreatePipe = 'CantCreatePipe',
+	CantAccessRemote = 'CantAccessRemote',
+	RepositoryNotFound = 'RepositoryNotFound',
+	RepositoryIsLocked = 'RepositoryIsLocked',
+	BranchNotFullyMerged = 'BranchNotFullyMerged',
+	NoRemoteReference = 'NoRemoteReference',
+	InvalidBranchName = 'InvalidBranchName',
+	BranchAlreadyExists = 'BranchAlreadyExists',
+	NoLocalChanges = 'NoLocalChanges',
+	NoStashFound = 'NoStashFound',
+	LocalChangesOverwritten = 'LocalChangesOverwritten',
+	NoUpstreamBranch = 'NoUpstreamBranch',
+	IsInSubmodule = 'IsInSubmodule',
+	WrongCase = 'WrongCase',
+	CantLockRef = 'CantLockRef',
+	CantRebaseMultipleBranches = 'CantRebaseMultipleBranches',
+	PatchDoesNotApply = 'PatchDoesNotApply',
+	NoPathFound = 'NoPathFound',
+	UnknownPath = 'UnknownPath',
+}

src/main.ts

@@ -1,22 +1,20 @@
 import * as http from 'http';
 import * as vscode from 'vscode';
+import { Repository } from './git';
 
 export async function activate(context: vscode.ExtensionContext) {
 	console.log('Successfully activated "WhatTheCommit"');
 
 	context.subscriptions.push(vscode.commands.registerCommand("wtc.getCommitMessage",
-		async () => {
-			const gitExtension = vscode.extensions.getExtension('vscode.git').exports;
-			const repo = gitExtension.getAPI(1).repositories[0];
-
+		async (repository: Repository) => {
 			http.get("http://www.whatthecommit.com/index.json", (resp) => {
 				let data = '';
 				resp.on('data', (chunk) => {
 					data += chunk;
 				});
 				resp.on('end', () => {
 					let myData = JSON.parse(data);
-					repo.inputBox.value = myData.commit_message;
+					repository.inputBox.value = myData.commit_message;
 					// vscode.window.showInformationMessage(myData.commit_message);
 				});
 			}).on("error", (err) => {