[FIX] emc: cooperator computation issue

False value treated as a string when no share_product code was registered.

easy_my_coop/models/partner.py

@@ -84,7 +84,9 @@ class ResPartner(models.Model):
         for partner in self:
             share_type = ''
             for line in partner.share_ids:
-                share_type = str(line.share_product_id.default_code)
+                code = line.share_product_id.default_code
+                if code:
+                    share_type = str(code)
             if share_type != '':
                 partner.cooperator_type = share_type