Don't allow builds when a package install is in progress

[KyleAMathews]

Gorgeous app! Was really fun playing around with it a bit tonight.

I did manage to cause a build failure on accident. I added a new dependency (super nice) and while it was installing, somewhat absent-mindedly started a build which then failed of course because some of the dependencies had been deleted or moved around or whatever due to the ongoing install.

[KyleAMathews]

Oh just noticed this also broke the develop server which was also running. Which is probably something we need to fix as we could probably detect this and die and restart (maybe?).

[joshwcomeau]

Hi Kyle! Thanks for checking Guppy out, glad you enjoyed it :D It's still super early days, but I'm excited to see where it goes from here.

There's some general weirdness with trying to do things while deps are installing (tracked in #33). My current not-very-great solution is to disable all dependency actions while one is in progress (since yeah trying to install a dependency while one is already installing will fail, as the package.json is currently write-locked). I could extend that solution to disable tasks while dependencies are installing.

It's very odd that it crashed the dev server! I don't remember running into that. I'll see if I can reproduce and follow-up if I can't for more info.

[joshwcomeau]

Alright, finally had some time to dig into this!

I wasn't able to reproduce this error. I tried the following:

• Create a new Gatsby project
• Start the development server
• Start installing a new dependency (hello)
• While it was installing, start a build

I repeated this a couple times with different dependencies (redux, lodash), as well as tried other things like formatting, and stopping/starting the dev server during installation.

@KyleAMathews if you can reproduce, can you share what the build failure + dev server crash were? For the dev server crash, I think we should be able to intercept that error and trigger a restart. For the build failure, we can just append additional error logs, something like "This may have failed because a dependency install was in progress. Please try again once the dependency installation has completed".

[joshwcomeau]

Ah, so I was actually able to replicate the build failure:

It's disguised as a success, so I probably didn't notice it in my earlier testing.

It should be an easy fix; disable builds while there's an active dependency queue for the project. Will tackle shortly.

(have not been able to replicate the dev-server crash 🤔)