Router: handle Lit.Unit and empty ArgClause #5652

Job	Run time
formatting	21s
test (11, windows-latest)	10m 44s
community-test (11, windows-latest, Scala2)	15m 16s
test (11, ubuntu-latest)	8m 24s
native-image (macOS-latest, default)	6m 2s
community-test (11, windows-latest, Scala3)	13m 56s
test (21, windows-latest)	10m 10s
native-image (ubuntu-latest, default)	3m 38s
test-scala-native (windows-latest)	10m 1s
community-test (11, windows-latest, Spark)	23m 51s
test (21, ubuntu-latest)	7m 44s
test-scala-native (ubuntu-latest)	6m 48s
native-image (ubuntu-latest, musl)	3m 46s
community-test (11, windows-latest, Intellij)	17m 53s
community-test (11, windows-latest, Other)	20m 11s
community-test (11, ubuntu-latest, Scala2)	13m 47s
community-test (11, ubuntu-latest, Scala3)	12m 47s
community-test (11, ubuntu-latest, Spark)	22m 12s
community-test (11, ubuntu-latest, Intellij)	15m 47s
community-test (11, ubuntu-latest, Other)	17m 25s
dockerize	0s
	4h 0m 43s

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