using uCalcSoftware;

var uc = new uCalc();
var t = uc.NewTransformer();
var logText = "ERROR: Fail 1. INFO: OK. ERROR: Fail 2. ERROR: Fail 3.";
t.Text = logText;

var errorRule = t.Pattern("ERROR: {msg}.");
// Stop after finding the first error to focus on the initial problem.
errorRule.StopAfter = 1;
t.Find();

Console.WriteLine($"First error found: {t.Matches.Text}");