Exception printing for plain strings prints "undefined"

[augustl]

If a test or implementation does this:

throw new Error("Hello, world");

The reporters will print:

"Error: Hello, world"

If a test or implementation does this:

throw "Hello, world";

The reporters will print (in the same color as the error above):

undefined

[dominykas]

Should you even be throwing strings around?

[dwittner]

Maybe not, but you can. Thus we should be able to handle that, in my opinon. A colored output of "undefined" feels like a bug.