cubicweb #3381670 attribute error in ajax_error_handler hide actual error [validation pending]

prioritynormal
typebug
done in3.17.12
load left0.000
closed by#946aded614f3 [web error] exception may not have a 'status' attribute, generating an AttributeError that hides the original error. Closes #3381670
patch[web error] exception may not have a 'status' attribute, generating an AttributeError that hides the original error. Closes #3381670 [applied]