catch any exception on `singletonclass` #1780

Job	Run time
ruby-versions / Generate Ruby versions	3s
test (2.7)	1m 48s
test (3.1)	1m 48s
test (3.0)	1m 36s
test (3.2)	1m 45s
test (debug)	6m 7s
test (3.4)	1m 52s
test (3.3)	1m 53s
test (head)	1m 42s
	18m 34s

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