I think BIRT is handled in the "Other
Java Products and Servers" forum. There used to be a list of the primary items covered in a forum, but I don't see it now.
Anyway, this item: /ThemesReportItems31.rptlibrary is something that (per the
J2EE standard), is being searched for in the root of the webapp WAR file (or directory). So if I exploded "myapp.war", that would be "TOMCAT_HOME/webapps/myapp/ThemesReportItems31.rptlibrary".
The other item that kept showing up was "file:///C:/apache-tomcat-9.0.0.M21/bin/test.chart". This one bothers me because firstly, it's generally not good practice to be dropping files into Tomcat's bin directory, and secondly, the bin directory is supposed to contain executable files, and a file named "test.chart" sounds more like a data file.
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.