AssertionError for shared append expression
The Saxon XSLT and XQuery processor, developed by Saxonica
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mhkay
Saxon throws an AssertionError with the message "base of shared append expression is of class class XYZ"
This happens when the query contains an expression of the form ($x, ABCD) where the first item is a variable reference, and the optimizer decides to inline the variable reference with the expression to which it is bound (which is done when a variable is only used once).
A patch is being placed in Subversion.
Fixed in 9.4.0.2