Huh, I was expecting my phone's calculator to return i, but it just says it's undefined. You'd think imaginary numbers should be supported, but I guess not. Maybe some phone calculators do, and some don't?
I mean, it's kind of funny, but also not a great user experience. If you're familiar with complex numbers, then you're left annoyed that it won't perform the computation. If you're not familiar with complex numbers, then you don't get the joke and it's not a helpful error message.