fix(dynamic-import-vars): Allow a "no files found" error to be emitted as warning (#1625)

* allow no files error to be emitted as warning

* Update packages/dynamic-import-vars/README.md

Co-authored-by: Andrew Powell <[email protected]>

---------

Co-authored-by: Andrew Powell <[email protected]>

Author: Kristján Oddsson

packages/dynamic-import-vars/README.md

@@ -68,6 +68,8 @@ Default: `false`
 
 By default, the plugin will not throw errors when target files are not found. Setting this option to true will result in errors thrown when encountering files which don't exist.
 
+⚠️ _Important:_ Enabling this option when `warnOnError` is set to `true` will result in a warning and _not_ an error
+
 #### `warnOnError`
 
 Type: `Boolean`<br>

packages/dynamic-import-vars/src/index.js

@@ -56,11 +56,14 @@ function dynamicImportVariables({ include, exclude, warnOnError, errorWhenNoFile
             );
 
             if (errorWhenNoFilesFound && paths.length === 0) {
-              this.error(
-                new Error(
-                  `No files found in ${glob} when trying to dynamically load concatted string from ${id}`
-                )
+              const error = new Error(
+                `No files found in ${glob} when trying to dynamically load concatted string from ${id}`
               );
+              if (warnOnError) {
+                this.warn(error);
+              } else {
+                this.error(error);
+              }
             }
 
             // create magic string if it wasn't created already

packages/dynamic-import-vars/test/rollup-plugin-dynamic-import-vars.test.js

@@ -218,7 +218,7 @@ test("doesn't throw if no files in dir when option isn't set", async (t) => {
   t.false(thrown);
 });
 
-test('throws if no files in dir when option is set', async (t) => {
+test('throws if no files in dir when `errorWhenNoFilesFound` is set', async (t) => {
   let thrown = false;
   try {
     await rollup({
@@ -236,3 +236,21 @@ test('throws if no files in dir when option is set', async (t) => {
   }
   t.true(thrown);
 });
+
+test('warns if no files in dir when `errorWhenNoFilesFound` and `warnOnError` are both set', async (t) => {
+  let warningEmitted = false;
+  await rollup({
+    input: 'fixture-no-files.js',
+    plugins: [dynamicImportVars({ errorWhenNoFilesFound: true, warnOnError: true })],
+    onwarn(warning) {
+      t.deepEqual(
+        warning.message,
+        `No files found in ./module-dir-c/*.js when trying to dynamically load concatted string from ${require.resolve(
+          './fixtures/fixture-no-files.js'
+        )}`
+      );
+      warningEmitted = true;
+    }
+  });
+  t.true(warningEmitted);
+});