solving problem with picto expressions (issue #478)

sails/src/api/models/Grid.js

@@ -90,7 +90,7 @@ module.exports = {
        .then((picto) => {
 
          // check picto has expressions associated manually or associated in student language
-         if (!picto.attributes.expression & (picto.expressions.length == 0 || picto.expressions[0].text.length == 0))
+         if (!stuPicto.attributes.expression & (picto.expressions.length == 0 || picto.expressions[0].text.length == 0))
            stuPicto.attributes.expression = sails.__({
              phrase: 'undef_label',
              locale: student.lang});