Allure collector should not try to build allure-report if no test reports are found

Allure collector try to run allure generate even if no test reports were found for given testplanId :

ERROR in allure.collector: Failed to open test resources or write results, on test plan id=2c9380858e412fa6018e42c72fe40004
java.io.IOException: Cannot run program "/bin/sh" (in directory "/tmp/allureReporting/2c9380858e412fa6018e42c72fe40004"): error=2, No such file or directory

This case should be log before trying to run the allure command. Moreover, the AllureCollectorOutput sent should warn the publisher of this problem before it tries to find the allure-report.tar