Fix ParserInteractive.accepts

[thekevinscott]

• Fixes bug with InteractiveParser.accepts()
• Adds node_modules to .gitignore (node modules should not be added to the repo)

[erezsh]

(Yes, the failure is due to the Lark python version not being pinned. We'll try again later)

[thekevinscott]

Though this fixes the specific bug I encountered, I may have introduced another bug.

Should t refer to the key of the choices dictionary, or the value?

It seems like it should be referencing the key, as far as I can tell from poking around my generated parser, but in this PR I have it referencing the dict's value.