Fix broken exception messages #89

Job	Run time
ruby-versions / Generate Ruby versions	2s
build (2.3 / ubuntu-latest)	25s
build (2.3 / macos-latest)	52s
build (2.4 / ubuntu-latest)	16s
build (2.4 / macos-latest)	1m 13s
build (2.5 / ubuntu-latest)	18s
build (2.5 / macos-latest)	58s
build (2.6 / ubuntu-latest)	22s
build (2.6 / macos-latest)	46s
build (2.7 / ubuntu-latest)	20s
build (2.7 / macos-latest)	42s
build (3.0 / ubuntu-latest)	10s
build (3.0 / macos-latest)	10s
build (3.1 / ubuntu-latest)	8s
build (3.1 / macos-latest)	18s
build (3.2 / ubuntu-latest)	10s
build (3.2 / macos-latest)	14s
build (head / ubuntu-latest)	7s
build (head / macos-latest)	15s
build (jruby / ubuntu-latest)	32s
build (jruby / macos-latest)	51s
build (jruby-head / ubuntu-latest)	32s
build (jruby-head / macos-latest)	1m 12s
build (truffleruby / ubuntu-latest)	22s
build (truffleruby / macos-latest)	40s
build (truffleruby-head / ubuntu-latest)	23s
build (truffleruby-head / macos-latest)	31s
	12m 49s

Provide feedback