As an User I get a meaningful error message when issue types in schemes are not correct

As an User I get a meaningful error message when issue types in schemes are not correct.

When importing automated test reports and the issue types are not correctly configured in the schemes, we get an error:
"Upload Failed! Status:500 Response:java.lang.NullPointerException"

A more helpful message should be provided so that the problem in the schemes can be fix.