fix: warn when an asset is skipped at the package boundary

src/analyze.ts

@@ -1299,15 +1299,18 @@ export default async function analyze(
         'node_modules' +
         path.sep;
       if (!assetPath.startsWith(nodeModulesBase)) {
-        if (job.log)
-          console.log(
-            'Skipping asset emission of ' +
-              assetPath +
-              ' for ' +
-              id +
-              ' as it is outside the package base ' +
-              pkgBase,
-          );
+        const message =
+          'Skipping asset emission of ' +
+          assetPath +
+          ' for ' +
+          id +
+          ' as it is outside the package base ' +
+          pkgBase;
+        // Also surfaced as a warning, not only under `job.log`: the file is otherwise
+        // simply absent from the output, so the first symptom is a runtime failure in
+        // the deployed application rather than anything visible at build time.
+        job.warnings.add(new Error(message));
+        if (job.log) console.log(message);
         return;
       }
     }

test/unit.test.js

@@ -176,7 +176,7 @@ for (const { testName, isRoot } of unitTests) {
         // Ignore.
       }
 
-      const { fileList, reasons } = await nodeFileTrace(
+      const { fileList, reasons, warnings } = await nodeFileTrace(
         inputFileNames.map((file) => join(unitPath, file)),
         {
           conditions: testOpts.conditions,
@@ -216,6 +216,19 @@ for (const { testName, isRoot } of unitTests) {
 
       const getReasonType = (f) => reasons.get(normalizeInputRoot(f)).type;
 
+      // Only on the uncached pass: the second run replays cached analysis and does not
+      // re-emit warnings.
+      if (!cached && testName === 'pkg-cwd-asset-outside-pkg-base') {
+        // The asset stays out of the output, but the skip has to be reported: silently
+        // omitting a file the package reads at runtime only surfaces once the deployed
+        // application fails.
+        expect(
+          [...warnings].some((warning) =>
+            warning.message.startsWith('Skipping asset emission of'),
+          ),
+        ).toBe(true);
+      }
+
       if (testName === 'multi-input') {
         const collectFiles = (parent, files = new Set()) => {
           fileList.forEach((file) => {

test/unit/pkg-cwd-asset-outside-pkg-base/.gitignore

@@ -0,0 +1 @@
+!node_modules

test/unit/pkg-cwd-asset-outside-pkg-base/input.js

@@ -0,0 +1 @@
+require('some-pkg');

test/unit/pkg-cwd-asset-outside-pkg-base/output.js

@@ -0,0 +1,6 @@
+[
+  "package.json",
+  "test/unit/pkg-cwd-asset-outside-pkg-base/input.js",
+  "test/unit/pkg-cwd-asset-outside-pkg-base/node_modules/some-pkg/index.js",
+  "test/unit/pkg-cwd-asset-outside-pkg-base/node_modules/some-pkg/package.json"
+]

test/unit/pkg-cwd-asset-outside-pkg-base/some.config.js

@@ -0,0 +1 @@
+module.exports = { config: true };