catch any exception on `singletonclass` #1779

Job	Run time
ruby-versions / Generate Ruby versions	5s
test (2.7)	1m 57s
test (3.0)	1m 58s
test (debug)	6m 7s
test (3.1)	1m 53s
test (3.3)	1m 53s
test (3.2)	2m 9s
test (3.4)	1m 48s
test (head)	1m 45s
ruby-versions / Generate Ruby versions	5s
test (3.2)	2m 12s
test (head)	1m 50s
test (3.0)	1m 55s
test (debug)	6m 15s
test (3.1)	1m 53s
test (2.7)	1m 57s
test (3.4)	1m 48s
test (3.3)	1m 53s
	39m 23s

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