Consider switching to tiny-invariant or own invariant function

[davidje13]

The use of invariant pulls in loose-envify which in turn pulls in js-tokens. This has little consequence when used with React since it already uses them, but when used outside React these are relatively heavy dependencies (as already noted in #126)

Also as noted in #83 (comment), this way of writing invariant checks can cause significant performance penalty, since the error message arguments are always evaluated (unless combined with a compile-time code rewriter, but this project doesn't do that)

I would like to suggest at a minimum switching to use tiny-invariant, which is compatible with invariant except that it does not provide the %s formatting. The library still works with compile-time code rewriters and does not have any dependencies (and is tiny itself).

And better would be to also run the code through a transformer as part of the build process so that the built code only evaluates error arguments if the condition fails (or see my suggested improvement to tiny-invariant alexreardon/tiny-invariant#62 if a build-time transformation is not desirable).