Stop and error if dependencies fail to install

[jsjoeio]

Right now, builds in CI keep going even if it times out downloading dependencies. Instead it should error and stop the build. This would improve our CI process.

[oxy]

I'm not entirely sure why it doesn't stop immediately; we use set -euo pipefail in all our shell scripts, which should in theory make bash exit with an error if a step fails. Does GitHub's CI just keep running even when one stage returns an error?

[code-asher]

As far as I can tell it's not specific to CI; the `yarn` command itself just isn't exiting with a non-zero code. I've seen a few reports from users exhibiting the same issue. So far they've all been network-related; maybe `yarn` has a bug where it doesn't exit with non-zero when that happens. Or probably more likely it has something to do with how the postinstall is set up.

[code-asher]

Might make sense to also check for the required system dependencies listed here: https://github.com/cdr/code-server/blob/v3.9.0/docs/npm.md

But possibly yarn is already erroring when it can't build due to missing system dependencies and we're just losing that somewhere.

[jsjoeio]

Check to make sure that ripgrep exists to prevent #3117