src/vs/platform/extensionManagement/node/extensionManagementService.ts/ExtensionsScanner/joinErrors
class ExtensionsScanner:	private joinErrors(errorOrErrors: (Error | string) | (Array<Error | string>)): Error {
		const errors = Array.isArray(errorOrErrors) ? errorOrErrors : [errorOrErrors];
		if (errors.length === 1) {
			return errors[0] instanceof Error ? <Error>errors[0] : new Error(<string>errors[0]);
		}
		return errors.reduce<Error>((previousValue: Error, currentValue: Error | string) => {
			return new Error(`${previousValue.message}${previousValue.message ? ',' : ''}${currentValue instanceof Error ? currentValue.message : currentValue}`);
		}, new Error(''));
	}