Not exactly. If the property truly was missing your ternary would work. But because the test sets the property to undefined and that is then explicitly converted to a string it ends up as a truthy value.
But just to be clear, I wouldn’t suggest using the logic you are. You would normally look for the string value on the environment variable (e.g. ‘development’). Especially because often the same property might contain different string values depending on what is needed. So just looking for a truthy value wouldn’t work.
I made an issue and a PR, but there may be some disagreement about how it should be fixed.