simple code

models.py

@@ -17,7 +17,6 @@ class res_partner_strip_email(models.Model):
         return super(res_partner_strip_email, self).create(vals)
 
     def _check_email_field(self, vals):
-        if not isinstance(vals['email'], bool) and 'email' in vals or \
-                isinstance(vals['email'], bool) and vals['email']:
+        if vals.get('email'):
             vals['email'] = vals['email'].strip()
         return vals