jspm_packages/system-polyfills.src.js
function formatError(e) {
		var s = typeof e === 'object' && e !== null && (e.stack || e.message) ? e.stack || e.message : formatObject(e);
		return e instanceof Error ? s : s + ' (WARNING: non-Error used)';
	}
function formatError(e) {
		var s = typeof e === 'object' && e !== null && (e.stack || e.message) ? e.stack || e.message : formatObject(e);
		return e instanceof Error ? s : s + ' (WARNING: non-Error used)';
	}
function formatError ( e ) { var s = typeof e === 'object' && e !== null && ( e . stack || e . message ) ? e . stack || e . message : formatObject ( e ) ; return e instanceof Error ? s : s + ' (WARNING: non-Error used)' ; }
Format an error into a string.  If e is an Error and has a stack property,
it's returned.  Otherwise, e is formatted using formatObject, with a
warning added about e not being a proper Error.
@param {*} e
@returns {String} formatted string, suitable for output to developers
Format an error into a string . If e is an Error and has a stack property it s returned . Otherwise e is formatted using formatObject with a warning added about e not being a proper Error .