diff -U3 /tmp/cirrus-ci-build/contrib/citext/expected/citext.out /tmp/cirrus-ci-build/contrib/citext/results/citext.out
--- /tmp/cirrus-ci-build/contrib/citext/expected/citext.out	2025-12-08 15:21:24.420630432 +0000
+++ /tmp/cirrus-ci-build/contrib/citext/results/citext.out	2025-12-08 15:26:57.982181315 +0000
@@ -10,6 +10,11 @@
 --------+---------
 (0 rows)
 
+SELECT CAST('abc'::bpchar AS citext DEFAULT NULL ON CONVERSION ERROR); --error
+ERROR:  cannot cast type character to citext when DEFAULT expression is specified in CAST ... ON CONVERSION ERROR
+LINE 1: SELECT CAST('abc'::bpchar AS citext DEFAULT NULL ON CONVERSI...
+                    ^
+HINT:  Safe type cast for user-defined types are not yet supported
 -- Test the operators and indexing functions
 -- Test = and <>.
 SELECT 'a'::citext = 'a'::citext AS t;