Errors Vs. Error causes Vs. Error Symptoms Vs. Error result in Testing

Assuming that there is a method in a system that accepts input value from the user for variable x and when the tester tried to enter a float number as a testcase, the system crashed!

My questions are:

• what can be the error?
• what are the error symptoms?

Given that:

• error cause --> variable x is defined as int
• error result --> system crash

Thanks :)