Fix configurator error in progress report page

progress report shows an error like this:

![progress report page showing error 500](/uploads/6857ba9d8405d1bbba35b0857bc765d8/Screenshot_2020-04-17_at_18.04.03.png)

See merge request !1103
2 jobs for feat/assorted_bug_fixes
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

passed ERP5.PerformanceTest-Master