onError method
Called when an error occurs
Implementation
@override
void onError(String method, String url, dynamic error) {
if (!enabled || !this.error) return;
// Clean up timestamp
_requestTimestamps.remove(url);
final errorBlock = StringBuffer();
errorBlock.writeln('╔╣ Error ║ $method');
errorBlock.writeln('║ $url');
errorBlock.writeln('║ $error');
errorBlock.write('╚ ${_repeatChar('═', maxWidth)}');
logPrint(errorBlock.toString());
}