ci: mandatory eslint rules for build

This commit adds verification for statically identifiable definite
errors. Sometimes global variables used will be falsely reported as
undefined variables in which case the new file
`mandatory.eslint.config.js` should be updated to include these
definitions in the narrowest scope possible that has these definitions

eslint/mandatory.eslint.config.js

@@ -0,0 +1,86 @@
+import tseslintPlugin from '@typescript-eslint/eslint-plugin';
+import { defineConfig } from 'eslint/config';
+import globals from 'globals';
+
+const backendLanguageOptions = {
+    globals: {
+        // Current, intentionally supported globals
+        extension: 'readonly',
+        config: 'readonly',
+        global_config: 'readonly',
+
+        // Older not entirely ideal globals
+        use: 'readonly', // <-- older import mechanism
+        def: 'readonly', // <-- older import mechanism
+        kv: 'readonly', // <-- should be passed/imported
+        ll: 'readonly', // <-- questionable
+
+        // Language/environment globals
+        ...globals.node,
+    },
+};
+
+export default defineConfig([
+    {
+        ignores: [
+            'src/backend/src/modules/apps/AppInformationService.js', // TEMPORARY - SHOULD BE FIXED!
+            'src/backend/src/services/worker/WorkerService.js', // TEMPORARY - SHOULD BE FIXED!
+            'src/backend/src/public/**/*', // We may be able to delete this! I don't think it's used
+
+            // These files run in the worker environment, so these rules don't apply
+            'src/backend/src/services/worker/dist/**/*.{js,cjs,mjs}',
+            'src/backend/src/services/worker/src/**/*.{js,cjs,mjs}',
+            'src/backend/src/services/worker/template/puter-portable.js',
+        ],
+    },
+    {
+        plugins: {
+            '@typescript-eslint': tseslintPlugin,
+        },
+    },
+    {
+        files: [
+            'src/backend/**/*.{js,mjc,cjs}',
+            'extensions/**/*.{js,mjc,cjs}',
+            'src/backend-core-0/**/*.{js,mjc,cjs}',
+        ],
+        ignores: [
+            'src/backend/src/services/database/sqlite_setup/**/*.js',
+        ],
+        rules: {
+            'no-undef': 'error',
+        },
+        languageOptions: {
+            ...backendLanguageOptions,
+        },
+    },
+    {
+        files: [
+            'src/backend/src/services/database/sqlite_setup/**/*.js',
+        ],
+        rules: {
+            'no-undef': 'error',
+        },
+        languageOptions: {
+            globals: {
+                read: 'readonly',
+                write: 'readonly',
+                log: 'readonly',
+                ...globals.node,
+            },
+        },
+    },
+    {
+        files: [
+            'src/backend/**/*.{ts}',
+            'extensions/**/*.{ts}',
+            'src/backend-core-0/**/*.{ts}',
+        ],
+        rules: {
+            'no-undef': 'error',
+        },
+        languageOptions: {
+            ...backendLanguageOptions,
+        },
+    },
+]);

package.json

@@ -44,7 +44,7 @@
     "start": "node ./tools/run-selfhosted.js",
     "prestart": "npm run build:ts",
     "dev": "npm run build:ts && DEVCONSOLE=1 node ./tools/run-selfhosted.js",
-    "build": "npm run build:ts; cd src/gui; node ./build.js",
+    "build": "npx eslint --quiet -c eslint/mandatory.eslint.config.js src/backend/src extensions && npm run build:ts && cd src/gui && node ./build.js",
     "check-translations": "node tools/check-translations.js",
     "prepare": "husky",
     "build:ts": "tsc",