fix: gracefully support empty config files (again) (#26)

.changeset/dirty-phones-chew.md

@@ -0,0 +1,5 @@
+---
+"@proload/core": patch
+---
+
+Gracefully support empty config files (again)

fixtures/empty-export/test.config.mjs

@@ -0,0 +1 @@
+export const other = true;

packages/core/lib/esm/index.mjs

@@ -237,6 +237,19 @@ async function load(namespace, opts = {}) {
 
   let rawValue = await requireOrImportWithMiddleware(filePath);
   if (filePath.endsWith('package.json')) rawValue = rawValue[namespace];
+  // Important: "empty" config files will be returned as `Module {}`
+  // We should handle them here
+  if (rawValue && !(rawValue instanceof Object)) {
+    if (mustExist) {
+      assert(
+        true,
+        `Resolved a ${namespace} configuration, but no configuration was exported`,
+        "ERR_PROLOAD_NOT_FOUND"
+      );
+    } else {
+      return;
+    }
+  }
   const resolvedValue = await resolveExtensions(namespace, {
     filePath,
     value: rawValue,

packages/core/test/index.mjs

@@ -32,6 +32,36 @@ test('missing but not mustExist', async () => {
     type(mdl, 'undefined')
 });
 
+test('empty but not mustExist', async () => {
+    let mdl = await load('test', { cwd: resolve(`fixtures/empty`), mustExist: false });
+    type(mdl, 'undefined')
+});
+
+test('empty but mustExist (default)', async () => {
+    let err = 0;
+    try {
+        let mdl = await load('test', { cwd: resolve(`fixtures/empty`) });
+    } catch (e) {
+        err += 1;
+    }
+    is(err, 1);
+});
+
+test('empty export but not mustExist', async () => {
+    let mdl = await load('test', { cwd: resolve(`fixtures/empty-export`), mustExist: false });
+    type(mdl, 'undefined')
+});
+
+test('empty export but mustExist (default)', async () => {
+    let err = 0;
+    try {
+        let mdl = await load('test', { cwd: resolve(`fixtures/empty-export`) });
+    } catch (e) {
+        err += 1;
+    }
+    is(err, 1);
+});
+
 const throwFixtures = ['ts', 'ts-config', 'json', 'json-config'];
 
 for (const fixture of throwFixtures) {