Index: src/ResolvExpr/Resolver.cc
===================================================================
--- src/ResolvExpr/Resolver.cc	(revision b834e98393306fc30c2857f5d569dc319f987d67)
+++ src/ResolvExpr/Resolver.cc	(revision a974dad9524d0d809130a28c041980aa42b18f00)
@@ -155,5 +155,5 @@
 		} // if
 		#endif
-		assertf( finder.get_alternatives().size() == 1, "findSingleExpression: must have exactly one alternative at the end." );
+		assertf( finder.get_alternatives().size() == 1, "findSingleExpression: must have exactly one alternative at the end: (%zd) %s", finder.get_alternatives().size(), toString( untyped ).c_str() );
 		Alternative &choice = finder.get_alternatives().front();
 		Expression *newExpr = choice.expr->clone();