segfault for ABNF range production about kgt HOT 7 CLOSED

; echo -e 'a = %x00-7F' | ./build/bin/kgt -l abnf -e rrtext 
a:
    ||--v-- "\x00" -->--||
        |            |
        |     :      |
        |            |
        `-- "\x7f" --'

; echo -e 'a = %x00-80' | ./build/bin/kgt -l abnf -e rrtext
a:
malloc: Cannot allocate memory
; 

; echo -e 'a = %x00-80' | ./build/bin/kgt -l abnf -e rrtdump
a: (before prettify)
    VLIST w=12 a=0 d=4294967295 o=0: [
        HLIST w=6 a=0 d=4294967295: [
            VLIST w=6 a=0 d=4294967295 o=0: [
            ]
        ]
    ]

; echo -e 'a = %x00-80' | ./build/bin/kgt -l abnf -e rrdump 
a: (before prettify)
    ALT: [
        SEQ: [
            ALT: [
            ]
        ]
    ]

; echo -e 'a = %xFE-FF' | ./build/bin/kgt -l abnf -e rrtdump
a: (before prettify)
    VLIST w=18 a=0 d=3 o=0: [
        HLIST w=12 a=0 d=3: [
            VLIST w=12 a=0 d=3 o=0: [
                HLIST w=6 a=0 d=1: [
zsh: done                echo -e 'a = %xFE-FF' | 
zsh: segmentation fault  ./build/bin/kgt -l abnf -e rrtdump