fix: deprecation warning (#415)

src/index.js

@@ -9,7 +9,11 @@ import LessError from "./LessError";
 async function lessLoader(source) {
   const options = this.getOptions(schema);
   const callback = this.async();
-  const lessOptions = getLessOptions(this, options);
+  const webpackContextSymbol = Symbol("loaderContext");
+  const lessOptions = getLessOptions(this, {
+    ...options,
+    webpackContextSymbol,
+  });
   const useSourceMap =
     typeof options.sourceMap === "boolean" ? options.sourceMap : this.sourceMap;
 
@@ -44,9 +48,7 @@ async function lessLoader(source) {
     return;
   }
 
-  if ("webpackLoaderContext" in less) {
-    delete less.webpackLoaderContext;
-  }
+  delete less[webpackContextSymbol];
 
   const { css, imports } = result;
 

src/utils.js

@@ -182,26 +182,27 @@ function getLessOptions(loaderContext, loaderOptions) {
     lessOptions.plugins.unshift(createWebpackLessPlugin(loaderContext));
   }
 
-  const webpackContextDeprecated = util.deprecate(
-    (context) => context,
-    "less.webpackLoaderContext is deprecated and will be removed in next major release. Instead use pluginManager.webpackLoaderContext (https://webpack.js.org/loaders/less-loader/#plugins)"
-  );
-
   lessOptions.plugins.unshift({
     install(lessProcessor, pluginManager) {
       // eslint-disable-next-line no-param-reassign
       pluginManager.webpackLoaderContext = loaderContext;
 
-      // Todo remove in next major release
-      if (typeof lessProcessor.webpackLoaderContext === "undefined") {
-        Object.defineProperty(lessProcessor, "webpackLoaderContext", {
-          configurable: true,
+      // Todo remove in next major release `lessProcessor[webpackContextSymbol]`
+      const { webpackContextSymbol } = options;
 
-          get() {
-            return webpackContextDeprecated(loaderContext);
-          },
-        });
-      }
+      // eslint-disable-next-line no-param-reassign
+      lessProcessor[webpackContextSymbol] = loaderContext;
+
+      Object.defineProperty(lessProcessor, "webpackLoaderContext", {
+        configurable: true,
+
+        get() {
+          util.deprecate(() => {},
+          "less.webpackLoaderContext is deprecated and will be removed in next major release. Instead use pluginManager.webpackLoaderContext (https://webpack.js.org/loaders/less-loader/#plugins)")();
+
+          return lessProcessor[webpackContextSymbol];
+        },
+      });
     },
   });