Outputting errors in messc again.

bin/messc

@@ -79,7 +79,9 @@ fs.readFile(input, 'utf-8', function (e, data) {
         local_data_dir: path.dirname(input),
     }).render(data, function(err, output) {
         if (err) {
-            mess.writeError(err, options);
+            err.forEach(function(e) {
+                mess.writeError(e, options);
+            });
             process.exit(1);
         } else {
             if (!options.benchmark) {

lib/mess/renderer.js

@@ -477,7 +477,7 @@ mess.Renderer = function Renderer(env) {
                         + '+nadgrids=@null +no_defs">\n');
 
                     output.push('</Map>');
-                    callback(null, output.join('\n'));
+                    callback(env.errors.length ? env.errors : null, output.join('\n'));
                 }
             );
         },