test

Add error when a terminal symbol is passed to `%nterm` #527

Job	Run time
check-misc (head)	9s
test-memory (head)	29s
steep-check (head)	30s
test-ruby (head, master)	5m 57s
test-ruby (3.0, master)	5m 55s
test-windows (head)	1m 31s
ruby-versions / Generate Ruby versions	3s
test-cpp (head, g++)	12s
test (2.5)	24s
test-cpp (head, clang++)	20s
test (2.6)	26s
test (2.7)	26s
test (3.0)	16s
test (3.1)	12s
test (3.2)	13s
test (3.3)	15s
test (head)	11s
	17m 29s

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