Print stack traces on error (#114)

* Print stack traces on error

* Append the original error message

* Move try/catch

* Fix catch block

* Revert, only generate code frames on module error

* Better logic for error code frame generation

src/Bundler.js

@@ -250,16 +250,18 @@ class Bundler extends EventEmitter {
     try {
       return await this.resolveAsset(dep.name, asset.name);
     } catch (err) {
-      err.message = `Cannot resolve dependency '${dep.name}'`;
+      if (err.message.indexOf(`Cannot find module '${dep.name}'`) === 0) {
+        err.message = `Cannot resolve dependency '${dep.name}'`;
+
+        // Generate a code frame where the dependency was used
+        if (dep.loc) {
+          await asset.loadIfNeeded();
+          err.loc = dep.loc;
+          err = asset.generateErrorMessage(err);
+        }
 
-      // Generate a code frame where the dependency was used
-      if (dep.loc) {
-        await asset.loadIfNeeded();
-        err.loc = dep.loc;
-        err = asset.generateErrorMessage(err);
+        err.fileName = asset.name;
       }
-
-      err.fileName = asset.name;
       throw err;
     }
   }