deleting '--' in parse object causes issues when argv is frozen

[bcoe]

We currently have logic that temporarily populates --, during command parsing, making it easier to differentiate between arguments after -- and positional arguments before --. We then delete this field post-parse, if the user did not request -- be populated.

Unfortunately, this creates an edge-case where if a user calls Object.seal or Object.freeze on argv, an exception can occur.

This logic is pretty silly, let's not do it -- there's already discussion of using a WeakMap to store information about whether or not parameters in argv have been deleted, I wonder if we could use a similar approach to track parameters after the --.

see: babel/babel#10733

[bcoe]

the try/catch logic has been working quite well.