Saxon

This typo (note the spurious “)” inside the putative QName):

 <xsl:variable name="dbe:INVALID-INJECT"
               select="xs:QName('dbe:INVALID-INJECT)')"/>

Causes an NPE in Saxon EE 10.0:

java.lang.NullPointerException
	at net.sf.saxon.expr.Expression.getRetainedStaticContext(Expression.java:462)
	at net.sf.saxon.expr.parser.LoopLifter.process(LoopLifter.java:50)
	at net.sf.saxon.expr.parser.ExpressionTool.optimizeComponentBody(ExpressionTool.java:1075)
	at net.sf.saxon.style.XSLGlobalVariable.optimize(XSLGlobalVariable.java:370)

Saxon spots the invalid QName at compile time and generates an ErrorExpression, but fails to assign it a RetainedStaticContext, causing the NPE when loop-lifting optimization later visits the expression.