fix: install latest node if setup-node fails (#186)

Continues if the setup-node action fails to install, and then installs
latest node if there is no node version installed. Judging by [this
website](https://node.green/) showing note compatibilities, node is
almost entirely backwards compatible, which is why I went with the
latest version rather than e.g. node 20.

Additionally, adds a node version to the package.json so that this PR
can merge - the v1 action version still chokes when not finding the node
version.

This is tested by adding the trunk-action repo to the [repo
tests](https://github.com/trunk-io/trunk-action/actions/runs/6156480974/job/16705376207?pr=186),
which does not have a node version in main. However, the runners have
node installed, so the action doesn't attempt to install a default
version - I'm not sure if there's a better way to test that/if it's
worth it.

.github/workflows/repo_tests.yaml

@@ -64,6 +64,14 @@ jobs:
             post-init: |
               ${TRUNK_PATH} check enable eslint
 
+          - repo: prawn-test-staging-rw/setup-node-test
+            ref: main
+            post-init: |
+              if [ "${FAILED_NODE_INSTALL}" != "true" ]; then
+                echo "::error::Initial setup node didn't fail"
+                exit 1
+              fi
+
           - repo: replayio/devtools
             ref: 730a9f0ddaafefc2a1a293d6924ce3910cd156ac
             description: (has trunk.yaml)

package.json

@@ -1,5 +1,8 @@
 {
   "dependencies": {
     "chai": "^4.3.7"
+  },
+  "engines": {
+    "node": "20.6.1"
   }
 }

setup-env/action.yaml

@@ -78,10 +78,32 @@ runs:
         version: latest
 
     - name: Install Node dependencies
+      id: setup_node
       if: env.PACKAGE_MANAGER && env.NODE_VERSION_FILE
       uses: actions/setup-node@v3
       with:
         node-version-file: ${{ env.NODE_VERSION_FILE }}
+      continue-on-error: true
+
+    - name: Check for node installation
+      if: env.PACKAGE_MANAGER && env.NODE_VERSION_FILE
+      shell: bash
+      run: |
+        if [ ${{ steps.setup_node.outcome }} == "success" ]; then
+          exit 0
+        fi
+        echo "::warning::Failed to install specified node version."
+        echo "FAILED_NODE_INSTALL=true" >>$GITHUB_ENV
+        if ! command -v node >/dev/null; then
+          echo "::warning::No existing node install detected - installing latest node instead."
+          echo "INSTALL_LATEST_NODE=true" >>$GITHUB_ENV
+        fi
+
+    - name: Install backup node version
+      if: env.PACKAGE_MANAGER && env.NODE_VERSION_FILE && env.INSTALL_LATEST_NODE == 'true'
+      uses: actions/setup-node@v3
+      with:
+        node-version-file: latest
 
     - name: Cache node_modules
       if: inputs.cache-key && env.PACKAGE_MANAGER