module: improve error message for invalid data URL

lib/internal/modules/esm/loader.js

@@ -6,12 +6,14 @@ require('internal/modules/cjs/loader');
 const {
   FunctionPrototypeBind,
   ObjectSetPrototypeOf,
+  RegExpPrototypeExec,
   SafeWeakMap,
   StringPrototypeStartsWith,
 } = primordials;
 
 const {
   ERR_INVALID_ARG_VALUE,
+  ERR_INVALID_MODULE_SPECIFIER,
   ERR_INVALID_RETURN_PROPERTY,
   ERR_INVALID_RETURN_PROPERTY_VALUE,
   ERR_INVALID_RETURN_VALUE,
@@ -107,6 +109,15 @@ class Loader {
     }
 
     const { format } = getFormatResponse;
+    if (format === null) {
+      const dataUrl = RegExpPrototypeExec(
+        /^data:([^/]+\/[^;,]+)(?:[^,]*?)(;base64)?,/,
+        url,
+      );
+      throw new ERR_INVALID_MODULE_SPECIFIER(
+        url,
+        dataUrl ? `has an unsupported MIME type "${dataUrl[1]}"` : '');
+    }
     if (typeof format !== 'string') {
       throw new ERR_INVALID_RETURN_PROPERTY_VALUE(
         'string', 'loader getFormat', 'format', format);

test/es-module/test-esm-data-urls.js

@@ -99,7 +99,7 @@ function createBase64URL(mime, body) {
       await import(plainESMURL);
       common.mustNotCall()();
     } catch (e) {
-      assert.strictEqual(e.code, 'ERR_INVALID_RETURN_PROPERTY_VALUE');
+      assert.strictEqual(e.code, 'ERR_INVALID_MODULE_SPECIFIER');
     }
   }
   {

test/es-module/test-esm-invalid-data-urls.js

@@ -0,0 +1,24 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+
+(async () => {
+  await assert.rejects(import('data:text/plain,export default0'), {
+    code: 'ERR_INVALID_MODULE_SPECIFIER',
+    message:
+      'Invalid module "data:text/plain,export default0" has an unsupported ' +
+      'MIME type "text/plain"',
+  });
+  await assert.rejects(import('data:text/plain;base64,'), {
+    code: 'ERR_INVALID_MODULE_SPECIFIER',
+    message:
+      'Invalid module "data:text/plain;base64," has an unsupported ' +
+      'MIME type "text/plain"',
+  });
+  await assert.rejects(import('data:application/json,[]'), {
+    code: 'ERR_INVALID_MODULE_SPECIFIER',
+    message:
+      'Invalid module "data:application/json,[]" has an unsupported ' +
+      'MIME type "application/json"',
+  });
+})().then(common.mustCall());