Don't attempt wasm-bindgen install if it exists in path.

[data-pup]

(Fixing issue #51.)

After running into some of the problems in the previous PR here, I squashed the commits from my previous PR down, and rebased it off of the recent changes to the repo.

In case there are issues with the Travis build again, here are the rust-fmt and rustc versions I am using.

✨  cargo fmt --version
rustfmt 0.4.1-nightly (e784712 2018-04-09)

✨  rustc --version
rustc 1.27.0-nightly (ad610bed8 2018-04-11)

Thank you for bearing with me on the linting problems by the way, pardon me.

[mgattozzi]

I'd just like to test this out locally but codewise I have no complaints! so it LGTM.

[ashleygwilliams]

the conflicts here are cuz i ran committed and merged more cargo fmt stuff, lemme know if you want help fixing that :) and i'll check this out tomorrow! thanks so much!

[data-pup]

Took a swing at fixing the merge conflict, the AppVeyor build failed with this message:

Downloading rustup-init.exe (4,701,696 bytes)...1%Error downloading remote file: One or more errors occurred.

That seems a little strange to me, not sure where to go from there.

[mgattozzi]

Build probably needs to be restarted. Their service probably had an error connecting to it is all!

[data-pup]

Added a note in the text to reference the issue being solved, per the pull request template checklist in pull #82. :)

[mgattozzi]

Hey @data-pup there's going to be a bit of churn today with getting 0.2 release out but would you be able to do a rebase in the next few days so we can work on getting your pr in? :D

[data-pup]

@mgattozzi Can do! I can get that done this afternoon. Congrats on 0.2 btw 🎉🙂

[mgattozzi]

@data-pup awesome! Maybe wait till we get the changelog pr in so you're not having to rebase again. There's no rush. Just wanted to make sure we're keeping an eye on this PR :)

[data-pup]

Sounds good! Feel free to ping me once things are in a good position for me to rebase from :)

[data-pup]

I went ahead and rebased this. I can do that again once #106 lands, but this hopefully gets all of the merging conflicts out of the way. 😀

I can also add some error handling to the wasm_bindgen_installed function and have it return a Result<(), Error> like you added in elsewhere. We mentioned that potentially being out of scope, but I wouldn't mind taking care of that too!

(Update: Took a swing at adding error handling, let me know if there are any changes there to make.)

[mgattozzi]

Since I put in a refactor for the error handling it's actually probably best that you put it in :)

[data-pup]

Rad :D If the error handling in there needs any changes, I can take another pass at it

[mgattozzi]

I think it's fine for now. Later on we'll be doing better error messages. I'll take a look at this on my Windows computer tonight :D

[data-pup]

Did #120 end up taking care of this? I can resolve the conflicts here if not :)

[ashleygwilliams]

heh yeah i was in the process of commenting on this @data-pup - i think the open question re https://github.com/ashleygwilliams/wasm-pack/issues/115 means this is a bit still on hold - the error PR from @mgattozzi shouldn't have affected this necessarily- the key question here is still how to manage installing wasm-bindgen. as that is still an open question, i think this PR is blocked for now, but i also think that this PR is getting us closer to an intermediate solution, so let's leave it open and see how 115 plays out.

[data-pup]

Sounds good :) I’ll keep an eye on that, let me know if anything changes!

[ashleygwilliams]

so i opened up a new issue about how we should address this- #146 i think we can use a lot of the work that's here as the basis for this. i'm already frustrated that we install wasm-bindgen everytime now lol. let me know if you have any thoughts or questsions, @data-pup !

[data-pup]

Awesome! That sounds good to me, when Alex confirms that the strategy mentioned over there would work I can wrap this up 😄 Thanks for following up on this @ashleygwilliams!