refactor: code

.github/workflows/nodejs.yml

@@ -55,7 +55,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        node-version: [10.x, 12.x, 13.x]
+        node-version: [10.x, 12.x, 14.x]
         webpack-version: [latest, next]
 
     runs-on: ${{ matrix.os }}

src/LessError.js

@@ -0,0 +1,33 @@
+class LessError extends Error {
+  constructor(error) {
+    super();
+
+    this.message = [
+      '\n',
+      ...LessError.getFileExcerptIfPossible(error),
+      error.message.charAt(0).toUpperCase() + error.message.slice(1),
+      `      Error in ${error.filename} (line ${error.line}, column ${error.column})`,
+    ].join('\n');
+
+    this.hideStack = true;
+  }
+
+  static getFileExcerptIfPossible(lessErr) {
+    if (lessErr.extract === 'undefined') {
+      return [];
+    }
+
+    const excerpt = lessErr.extract.slice(0, 2);
+    const column = Math.max(lessErr.column - 1, 0);
+
+    if (typeof excerpt[0] === 'undefined') {
+      excerpt.shift();
+    }
+
+    excerpt.push(`${new Array(column).join(' ')}^`);
+
+    return excerpt;
+  }
+}
+
+export default LessError;

src/createWebpackLessPlugin.js

@@ -98,15 +98,16 @@ function createWebpackLessPlugin(loaderContext) {
         result = await super.loadFile(filename, ...args);
       } catch (error) {
         if (error.type !== 'File' && error.type !== 'Next') {
-          loaderContext.emitError(error);
-
           return Promise.reject(error);
         }
 
         try {
           result = await this.resolveFilename(filename, ...args);
-        } catch (e) {
-          loaderContext.emitError(e);
+        } catch (webpackResolveError) {
+          error.message =
+            `Less resolver error:\n${error.message}\n\n` +
+            `Webpack resolver error details:\n${webpackResolveError.details}\n\n` +
+            `Webpack resolver error missing:\n${webpackResolveError.missing}\n\n`;
 
           return Promise.reject(error);
         }

src/getLessOptions.js

@@ -7,30 +7,9 @@ import createWebpackLessPlugin from './createWebpackLessPlugin';
  *
  * @param {object} loaderContext
  * @param {object} loaderOptions
- * @param {string} content
  * @returns {Object}
  */
-function getLessOptions(loaderContext, loaderOptions, content) {
-  function prependData(target, addedData) {
-    if (!addedData) {
-      return target;
-    }
-
-    return typeof addedData === 'function'
-      ? `${addedData(loaderContext)}\n${target}`
-      : `${addedData}\n${target}`;
-  }
-
-  function appendData(target, addedData) {
-    if (!addedData) {
-      return target;
-    }
-
-    return typeof addedData === 'function'
-      ? `${target}\n${addedData(loaderContext)}`
-      : `${target}\n${addedData}`;
-  }
-
+function getLessOptions(loaderContext, loaderOptions) {
   const options = clone(
     loaderOptions.lessOptions
       ? typeof loaderOptions.lessOptions === 'function'
@@ -39,17 +18,12 @@ function getLessOptions(loaderContext, loaderOptions, content) {
       : {}
   );
 
-  let data = content;
-  data = prependData(data, loaderOptions.prependData);
-  data = appendData(data, loaderOptions.appendData);
-
   const lessOptions = {
     plugins: [],
     relativeUrls: true,
     // We need to set the filename because otherwise our WebpackFileManager will receive an undefined path for the entry
     filename: loaderContext.resourcePath,
     ...options,
-    data,
   };
 
   lessOptions.plugins.push(createWebpackLessPlugin(loaderContext));

src/index.js

@@ -5,8 +5,7 @@ import validateOptions from 'schema-utils';
 
 import schema from './options.json';
 import getLessOptions from './getLessOptions';
-import removeSourceMappingUrl from './removeSourceMappingUrl';
-import formatLessError from './formatLessError';
+import LessError from './LessError';
 
 function lessLoader(source) {
   const options = getOptions(this);
@@ -17,28 +16,48 @@ function lessLoader(source) {
   });
 
   const callback = this.async();
-  const lessOptions = getLessOptions(this, options, source);
+  const lessOptions = getLessOptions(this, options);
+
+  let data = source;
+  data = prependData(data, options.prependData);
+  data = appendData(data, options.appendData);
 
   less
-    .render(lessOptions.data, lessOptions)
+    .render(data, lessOptions)
     .then(({ css, map, imports }) => {
       imports.forEach(this.addDependency, this);
 
       // Removing the sourceMappingURL comment.
       // See removeSourceMappingUrl.js for the reasoning behind this.
-      callback(
-        null,
-        removeSourceMappingUrl(css),
-        typeof map === 'string' ? JSON.parse(map) : map
-      );
+      callback(null, css, typeof map === 'string' ? JSON.parse(map) : map);
     })
     .catch((lessError) => {
       if (lessError.filename) {
         this.addDependency(lessError.filename);
       }
 
-      callback(formatLessError(lessError));
+      callback(new LessError(lessError));
     });
+
+  function prependData(target, addedData) {
+    if (!addedData) {
+      return target;
+    }
+
+    return typeof addedData === 'function'
+      ? `${addedData(this)}\n${target}`
+      : `${addedData}\n${target}`;
+  }
+
+  function appendData(target, addedData) {
+    if (!addedData) {
+      return target;
+    }
+
+    return typeof addedData === 'function'
+      ? `${target}\n${addedData(this)}`
+      : `${target}\n${addedData}`;
+  }
 }
 
 export default lessLoader;

test/__snapshots__/loader.test.js.snap

@@ -166,8 +166,6 @@ exports[`loader should provide a useful error message if the import could not be
 Array [
   "ModuleBuildError: Module build failed (from \`replaced original path\`):
 ",
-  "ModuleError: Module Error (from \`replaced original path\`):
-Can't resolve 'not-existing.less' in '/test/fixtures'",
 ]
 `;