throw together some continuous linter & formatter check

.github/workflows/code_check.yml

@@ -0,0 +1,13 @@
+name: Linter & Formatter Check
+on: push
+jobs:
+    build:
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v2
+            - name: Install modules
+              run: npm ci
+            - name: Run ESLint
+              run: npx eslint src --ext .mjs
+            - name: Run Prettier
+              run: npx prettier --check .