Confusing "advice" from the tool on already listed dependencies

[jvoigtlaender]

Having this:

    "dependencies": {
        "elm-lang/core": "2.1.0 <= v < 3.0.0",
        "evancz/start-app": "2.0.0 <= v < 2.0.1"
    },

in my elm-package.json, I run

elm-package install evancz/start-app

and get this message:

Error: This is a tricky update, you should modify elm-package.json yourself.
Package evancz/start-app is already listed as a dependency:

    "evancz/start-app": "2.0.0 <= v < 2.0.1"

You probably want one of the following constraints instead:

    2.0.0 <= v < 2.0.1
    2.0.1 <= v < 3.0.0

It's not immediately obvious to me from this message why what I'm trying to do is tricky or erroneous. I'm advised to modify elm-package.json myself, but that's exactly what I previously did by adding "evancz/start-app": "2.0.0 <= v < 2.0.1" there. So it's not clear what the tool is trying to tell me I should have done differently. (The answer probably is: I should call just elm-package install, not elm-package install evancz/start-app.)

But most confusingly, the message is telling me that I have specified 2.0.0 <= v < 2.0.1 but probably instead want 2.0.0 <= v < 2.0.1 (which is exactly what I already have!) or something else.