NPE when displaying a diff

[vladak]

When displaying a diff between two revisions in the latest master I am getting a NPE:

java.lang.NullPointerException
	at org.apache.jsp.diff_jsp._jspService(diff_jsp.java:722)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71)
	at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:770)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:467)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:379)
...

Looking at the diff_jsp.java file in the Tomcat's work directory I see it happens here:

} else if (data.getRevision().size() == 0) { 

[vladak]

This corresponds to

opengrok/opengrok-web/src/main/webapp/diff.jsp

Line 137 in b996a17

} else if (data.getRevision().size() == 0) {

In the debugger I see the revision field being null indeed.

[vladak]

Tracing the execution, this branch is taken:

opengrok/opengrok-web/src/main/java/org/opengrok/web/PageConfig.java

Lines 351 to 353 in b996a17

	if (Objects.isNull(data.errorMsg)) {
	return;
	}

so the revisions are not filled.

[vladak]

After flipping the condition, the diff starts working.

[vladak]

Introduced in 667c06e