Calling setup-jsonnet can fail without error

When using zendesk/setup-jsonnet, the installation can fail without error leading to difficult to diagnose failures later on.

There is an example usage here:

https://github.com/zendesk/entitlements/blob/3c68ee80b0d8470b84c07b2b26da8de3e19bcdc5/.github/workflows/spinnaker-manifests.yml#L88

And an example silent failure here https://github.com/zendesk/entitlements/runs/4207995033?check_suite_focus=true

Which can be observed by expanding the "Run zendesk/setup-jsonnet@v6" step.

I have reproduced the output below:

Run zendesk/setup-jsonnet@v7
  with:
    github_token: ***
    version: latest
  env:
    PROJECT_ID: docker-images-180022
    IMAGE_PATH: apps
    IMAGE_NAME: entitlements
    IMAGE_NAME2: entitlements-console
    IMAGE_NAME3: entitlements-debug
    ARTIFACTORY_API_KEY: ***
    ARTIFACTORY_USERNAME: ***
    DIGEST: sha256:2317cc52a1b3c6406191d0b292baf313a1037df69a99d4f23e2169caed5bb84e
    SHA: 66b31c16529f0ccc2953b54bc73f7d1232cad53c
/home/runner/runner/agent/_work/_actions/zendesk/setup-jsonnet/v7/install-jsonnet.sh
+ go get github.com/google/go-jsonnet/cmd/jsonnet
# cd .; git clone -- https://gopkg.in/yaml.v2 /home/runner/go/src/gopkg.in/yaml.v2
Cloning into '/home/runner/go/src/gopkg.in/yaml.v2'...
remote: Cannot obtain refs from GitHub: cannot talk to GitHub: Get https://github.com/go-yaml/yaml.git/info/refs?service=git-upload-pack: net/http: request canceled (Client.Timeout exceeded while awaiting headers)
fatal: unable to access 'https://gopkg.in/yaml.v2/': The requested URL returned error: 502
package gopkg.in/yaml.v2: exit status 128
(node:8460) UnhandledPromiseRejectionWarning: Error: The process '/home/runner/runner/agent/_work/_actions/zendesk/setup-jsonnet/v7/install-jsonnet.sh' failed with exit code 1
    at ExecState._setResult (/home/runner/runner/agent/_work/_actions/zendesk/setup-jsonnet/v7/node_modules/@actions/exec/lib/toolrunner.js:574:25)
    at ExecState.CheckComplete (/home/runner/runner/agent/_work/_actions/zendesk/setup-jsonnet/v7/node_modules/@actions/exec/lib/toolrunner.js:557:18)
    at ChildProcess.<anonymous> (/home/runner/runner/agent/_work/_actions/zendesk/setup-jsonnet/v7/node_modules/@actions/exec/lib/toolrunner.js:451:27)
    at ChildProcess.emit (events.js:210:5)
    at maybeClose (internal/child_process.js:1021:16)
    at Socket.<anonymous> (internal/child_process.js:430:11)
    at Socket.emit (events.js:210:5)
    at Pipe.<anonymous> (net.js:659:12)
(node:8460) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:8460) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Start with install-jsonnet.sh, which is invoked by the zendesk/setup-jsonnet action, and compare its behavior with the example workflow and failed run. Reproduce the dependency-download failure and verify that the action reports the installation error and fails the workflow instead of continuing silently.