if(temperature == -1) { // If there is an error with the TC, temperature will be -1
Serial.println("Thermocouple Error!!"); // Temperature is -1 and there is a thermocouple error
}
Hello. I'm a beginner as well, but I'm not sure that the Serial.Print above will ever be triggered.
Your temperature value is a float, hence to compare it with a fixed value is unwise. You need to ask 'is the absolute value of the difference between temperature and -1 less than some small, but arbitrary value (perhaps 0.0001)'?
In addition, because you do some maths on temperature before you do the test, your thermocouple would need to return 30.2 (if my maths is correct) for temperature to be -1.