parser: don’t exit(1) on invalid command, use better error message

[i3/i3] / testcases / Makefile

test:
        PERL_DL_NONLAZY=1 /usr/bin/perl "-MExtUtils::Command::MM" "-e" "test_harness(1)" -It/lib t/34*.t

all: test

testfull:
        PERL_DL_NONLAZY=1 /usr/bin/perl "-MExtUtils::Command::MM" "-e" "test_harness(1)" -It/lib t/01* t/02* t/03* t/05* t/17* t/18* t/19* t/20*