[NQP-rx] cannot support an empty string as token

[fperrad]

nqp-rx cannot support an empty string in a token.

$ cat token.nqp

token NonindentSpace { '   ' | '  ' | ' ' | '' }

$ parrot-nqp --target=pir token.nqp
Null PMC access in find_method('result')
current instr.: 'parrot;PAST;Compiler;post_regex' pc 4718 (src\stage0\Regex-s0.pir:2446)
called from Sub 'parrot;PAST;Compiler;concat' pc 6053 (src\stage0\Regex-s0.pir:2787)
called from Sub 'parrot;PAST;Compiler;post_regex' pc 4718 (src\stage0\Regex-s0.pir:2446)
called from Sub 'parrot;PAST;Compiler;alt' pc 4818 (src\stage0\Regex-s0.pir:2484)
called from Sub 'parrot;PAST;Compiler;post_regex' pc 4718 (src\stage0\Regex-s0.pir:2446)
called from Sub 'parrot;PAST;Compiler;concat' pc 6053 (src\stage0\Regex-s0.pir:2787)
called from Sub 'parrot;PAST;Compiler;post_regex' pc 4718 (src\stage0\Regex-s0.pir:2446)
called from Sub 'parrot;PAST;Compiler;as_post' pc 3995 (src\stage0\Regex-s0.pir:2231)
called from Sub 'parrot;PAST;Compiler;post_children' pc 2293 (src/PAST/Compiler.pir:412)
called from Sub 'parrot;PAST;Compiler;as_post' pc 3351 (src/PAST/Compiler.pir:774)
called from Sub 'parrot;PAST;Compiler;post_children' pc 2293 (src/PAST/Compiler.pir:412)
called from Sub 'parrot;PAST;Compiler;as_post' pc 2754 (src/PAST/Compiler.pir:625)
called from Sub 'parrot;PAST;Compiler;post_children' pc 2293 (src/PAST/Compiler.pir:412)
called from Sub 'parrot;PAST;Compiler;as_post' pc 3351 (src/PAST/Compiler.pir:774)
called from Sub 'parrot;PCT;HLLCompiler;compile' pc 388 (src\PCT\HLLCompiler.pir:287)
called from Sub 'parrot;PCT;HLLCompiler;eval' pc 992 (src\PCT\HLLCompiler.pir:556)
called from Sub 'parrot;PCT;HLLCompiler;evalfiles' pc 1303 (src\PCT\HLLCompiler.pir:707)
called from Sub 'parrot;PCT;HLLCompiler;command_line' pc 1489 (src\PCT\HLLCompiler.pir:794)
called from Sub 'parrot;NQP;Compiler;main' pc -1 ((unknown file):-1)

[pmichaud]

Now fixed in r43134. Thanks!

Pm