Add file and line number to @mdx/loader error output

packages/loader/lib/index.js

@@ -62,10 +62,19 @@ export function loader(value, callback) {
     map.set(hash, process)
   }
 
-  process({value, path: this.resourcePath}).then((file) => {
-    callback(null, file.value, file.map)
-    return file
-  }, callback)
+  process({value, path: this.resourcePath}).then(
+    (file) => {
+      callback(null, file.value, file.map)
+    },
+    (e) => {
+      let loc = '';
+      if (e.position) {
+        loc = `:${e.position.start.line}:${e.position.start.column}`;
+      }
+      e.message = `${e.message} while parsing ${this.resourcePath}${loc}`;
+      callback(e);
+    }
+  )
 }
 
 /**