parse in the try/catch

lib/mbtiles.js

@@ -253,11 +253,12 @@ MBTiles.prototype.grid = function(x, y, z, callback) {
                         memo[r.key_name] = JSON.parse(r.key_json);
                         return memo;
                     }, {});
+                var result = _(JSON.parse(grid)).extend({ data: data });
             } catch (err) {
                 return callback('Grid is invalid');
             }
 
-            callback(null, _(JSON.parse(grid)).extend({ data: data }));
+            callback(null, result);
         }
     );
 };