[jemfinch]

I don't know anyone who defines a "bug" as "an unexpected result as a product of good programming." Bugs are when code is wrong: when it doesn't do what it says, when it doesn't do what was asked of it, when it doesn't do what the user reasonably expects. Bugs are not the result of good programming.

[Wilduck]

I disagree. I would say there is a distinction between an error and a bug. There's certainly some grey area there, but, for example, if my code sets permissions for a directory instead of a file, I made an error. If my code sets permissions for a file, but produces unexpected results in certain cases because of an implementation detail, then that's a bug.

[eridius]

A bug is code that doesn't behave as the author intended it to. It doesn't matter if the bug is due to some subtle interaction in the language, or just plain bone-headedness on the part of the programmer.