Add the message in BabelLoaderError's stack trace (#499)

* Add the message in BabelLoaderError's stack trace

When Error.captureStackTrace is called at the top of BabelLoaderError,
the error name and message are not added to the stack property. When
webpack wraps this in a ModuleBuildError, the message is lost.

Capturing at the end of the function ensures the message is part of the
stack trace, so it is eventually added to webpack's output.

* Add test for BabelLoaderError's stack property

src/index.js

@@ -14,12 +14,13 @@ const fs = require("fs");
  */
 function BabelLoaderError(name, message, codeFrame, hideStack, error) {
   Error.call(this);
-  Error.captureStackTrace(this, BabelLoaderError);
 
   this.name = "BabelLoaderError";
   this.message = formatMessage(name, message, codeFrame);
   this.hideStack = hideStack;
   this.error = error;
+
+  Error.captureStackTrace(this, BabelLoaderError);
 }
 
 BabelLoaderError.prototype = Object.create(Error.prototype);

test/loader.test.js

@@ -263,3 +263,21 @@ test.cb("should not throw without config", t => {
     t.end();
   });
 });
+
+test.cb(
+  "should return compilation errors with the message included in the stack trace",
+  t => {
+    const config = Object.assign({}, globalConfig, {
+      entry: path.join(__dirname, "fixtures/syntax.js"),
+      output: {
+        path: t.context.directory,
+      },
+    });
+    webpack(config, (err, stats) => {
+      const moduleBuildError = stats.compilation.errors[0];
+      const babelLoaderError = moduleBuildError.error;
+      t.regex(babelLoaderError.stack, /Unexpected character/);
+      t.end();
+    });
+  },
+);