Show nicer message on syntax errors

Author: gaearon

scripts/rollup/build.js

@@ -416,13 +416,23 @@ function createBundle(bundle, bundleType) {
         console.error(error.message);
 
         const {file, line, column} = error.loc;
-        const rawLines = fs.readFileSync(file, 'utf-8');
-        // column + 1 is required due to rollup counting column start position from 0
-        // whereas babel-code-frame counts from 1
-        const frame = codeFrame(rawLines, line, column + 1, {
-          highlightCode: true,
-        });
-        console.error(frame);
+        if (file) {
+          // This looks like an error from Rollup, e.g. missing export.
+          // We'll use the accurate line numbers provided by Rollup but
+          // use Babel code frame because it looks nicer.
+          const rawLines = fs.readFileSync(file, 'utf-8');
+          // column + 1 is required due to rollup counting column start position from 0
+          // whereas babel-code-frame counts from 1
+          const frame = codeFrame(rawLines, line, column + 1, {
+            highlightCode: true,
+          });
+          console.error(frame);
+        } else {
+          // This looks like an error from a plugin (e.g. Babel).
+          // In this case we'll resort to displaying the provided code frame
+          // because we can't be sure the reported location is accurate.
+          console.error(error.codeFrame);
+        }
       } else {
         console.error(error);
       }