extensions/github-authentication/src/common/keychain.ts/Keychain/tryMigrate
class Keychain:	async tryMigrate(): Promise<string | null | undefined> {
		try {
			const keytar = getKeytar();
			if (!keytar) {
				throw new Error('keytar unavailable');
			}

			const oldValue = await keytar.getPassword(`${vscode.env.uriScheme}-github.login`, 'account');
			if (oldValue) {
				await this.setToken(oldValue);
				await keytar.deletePassword(`${vscode.env.uriScheme}-github.login`, 'account');
			}

			return oldValue;
		} catch (_) {
			// Ignore
			return Promise.resolve(undefined);
		}
	}