The backtrace start (taken from a patched lua_lpeg, so line numbers won't match with latest released version):

(gdb) bt -40
#523468 0x00007ffff6e4026c in hascaptures (tree=0xd1f57c, tree@entry=0xd1f58c) at lpcode.c:144
#523469 0x00007ffff6e4026c in hascaptures (tree=tree@entry=0xd1f584) at lpcode.c:144
#523470 0x00007ffff6e4026c in hascaptures (tree=0xd1f57c, tree@entry=0xd1f58c) at lpcode.c:144
#523471 0x00007ffff6e4026c in hascaptures (tree=tree@entry=0xd1f584) at lpcode.c:144
#523472 0x00007ffff6e4026c in hascaptures (tree=0xd1f57c, tree@entry=0xd1f58c) at lpcode.c:144
#523473 0x00007ffff6e4026c in hascaptures (tree=tree@entry=0xd1f584) at lpcode.c:144
#523474 0x00007ffff6e4026c in hascaptures (tree=0xd1f57c, tree@entry=0xd1f58c) at lpcode.c:144
#523475 0x00007ffff6e4026c in hascaptures (tree=tree@entry=0xd1f584) at lpcode.c:144
#523476 0x00007ffff6e4026c in hascaptures (tree=0xd1f57c, tree@entry=0xd1f58c) at lpcode.c:144
#523477 0x00007ffff6e4026c in hascaptures (tree=tree@entry=0xd1f584) at lpcode.c:144
#523478 0x00007ffff6e4026c in hascaptures (tree=0xd1f57c, tree@entry=0xd1f58c) at lpcode.c:144
#523479 0x00007ffff6e4026c in hascaptures (tree=tree@entry=0xd1f584) at lpcode.c:144
#523480 0x00007ffff6e4026c in hascaptures (tree=0xd1f57c, tree@entry=0xd1f5b4) at lpcode.c:144
#523481 0x00007ffff6e4026c in hascaptures (tree=tree@entry=0xd1f5ac) at lpcode.c:144
#523482 0x00007ffff6e410a4 in codecapture (fl=0x7ffff6e421c0 <fullset_>, tt=-1, tree=0xd1f5a4, compst=0x7fffffffcf10) at lpcode.c:720
#523483 codegen (compst=compst@entry=0x7fffffffcf10, tree=tree@entry=0xd1f5a4, opt=opt@entry=0, tt=tt@entry=-1, fl=fl@entry=0x7ffff6e421c0 <fullset_>) at lpcode.c:905
#523484 0x00007ffff6e41715 in codegrammar (compst=compst@entry=0x7fffffffcf10, grammar=grammar@entry=0xd1f4c4) at lpcode.c:850
#523485 0x00007ffff6e41023 in codegen (compst=compst@entry=0x7fffffffcf10, tree=tree@entry=0xd1f4c4, opt=opt@entry=0, tt=tt@entry=-1, fl=fl@entry=0x7ffff6e421c0 <fullset_>) at lpcode.c:907
#523486 0x00007ffff6e4188e in compile (L=0x2050cd0, p=0xd1f4b8) at lpcode.c:977
#523487 0x00007ffff6e3fdeb in lp_match (L=0x2050cd0) at lptree.c:1150
#523488 0x00007ffff70508ed in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523489 0x00007ffff705c4ed in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523490 0x00007ffff7050ae0 in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523491 0x00007ffff705026f in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523492 0x00007ffff7050cc7 in lua_resume () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523493 0x00007ffff7060f44 in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523494 0x00007ffff70612b1 in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523495 0x00007ffff70508ed in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523496 0x00007ffff705c4ed in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523497 0x00007ffff7050c2e in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523498 0x00007ffff704cccb in lua_callk () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523499 0x00000000004a5036 in run_main (L=0xca0cf0) at nse_main.cc:651
#523500 0x00007ffff70508ed in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523501 0x00007ffff7050c22 in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523502 0x00007ffff705026f in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523503 0x00007ffff7050e71 in ?? () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523504 0x00007ffff704cd91 in lua_pcallk () from /usr/lib/x86_64-linux-gnu/liblua5.2.so.0
#523505 0x00000000004a6524 in script_scan (targets=std::vector of length 1, capacity 100 = {...}, scantype=<optimized out>) at nse_main.cc:809
#523506 0x00000000004535e0 in nmap_main (argc=argc@entry=3, argv=argv@entry=0x7fffffffe5a8) at nmap.cc:2121
#523507 0x000000000042ab9b in main (argc=3, argv=0x7fffffffe5a8) at main.cc:228