* thread #5: tid = 21381, 0x00007f98c557904f libc.so.6`__GI_raise + 207, name = 'mserver5', stop reason = signal SIGABRT
    frame #0: 0x00007f98c557904f libc.so.6`__GI_raise + 207
libc.so.6`__GI_raise:
->  0x7f98c557904f <+207>: addq   $0x88, %rsp
    0x7f98c5579056 <+214>: movl   %r8d, %eax
    0x7f98c5579059 <+217>: popq   %rbx
    0x7f98c557905a <+218>: retq   
(lldb) bt
* thread #5: tid = 21381, 0x00007f98c557904f libc.so.6`__GI_raise + 207, name = 'mserver5', stop reason = signal SIGABRT
    frame #0: 0x00007f98c557904f libc.so.6`__GI_raise + 207
    frame #1: 0x00007f98c557a47a libc.so.6`__GI_abort + 362
    frame #2: 0x00007f98c5571ea7 libc.so.6`__assert_fail_base + 279
    frame #3: 0x00007f98c5571f52 libc.so.6`__GI___assert_fail + 66
  * frame #4: 0x00007f98c384578d lib_sql.so`rel2bin_semijoin(be=0x00007f98b40c1a90, rel=0x00007f98b40d6d90, refs=0x00007f98b40de4e0) + 770 at rel_bin.c:1905
    frame #5: 0x00007f98c3852065 lib_sql.so`subrel_bin(be=0x00007f98b40c1a90, rel=0x00007f98b40d6d90, refs=0x00007f98b40de4e0) + 379 at rel_bin.c:4724
    frame #6: 0x00007f98c384552c lib_sql.so`rel2bin_semijoin(be=0x00007f98b40c1a90, rel=0x00007f98b40d77e0, refs=0x00007f98b40de4e0) + 161 at rel_bin.c:1869
    frame #7: 0x00007f98c3852065 lib_sql.so`subrel_bin(be=0x00007f98b40c1a90, rel=0x00007f98b40d77e0, refs=0x00007f98b40de4e0) + 379 at rel_bin.c:4724
    frame #8: 0x00007f98c3847b6c lib_sql.so`rel2bin_project(be=0x00007f98b40c1a90, rel=0x00007f98b40da850, refs=0x00007f98b40de4e0, topn=0x0000000000000000) + 635 at rel_bin.c:2382
    frame #9: 0x00007f98c385211f lib_sql.so`subrel_bin(be=0x00007f98b40c1a90, rel=0x00007f98b40da850, refs=0x00007f98b40de4e0) + 565 at rel_bin.c:4740
    frame #10: 0x00007f98c3847b6c lib_sql.so`rel2bin_project(be=0x00007f98b40c1a90, rel=0x00007f98b40da950, refs=0x00007f98b40de4e0, topn=0x0000000000000000) + 635 at rel_bin.c:2382
    frame #11: 0x00007f98c385211f lib_sql.so`subrel_bin(be=0x00007f98b40c1a90, rel=0x00007f98b40da950, refs=0x00007f98b40de4e0) + 565 at rel_bin.c:4740
    frame #12: 0x00007f98c3852416 lib_sql.so`output_rel_bin(be=0x00007f98b40c1a90, rel=0x00007f98b40da950) + 102 at rel_bin.c:4805
    frame #13: 0x00007f98c3863390 lib_sql.so`sql_relation2stmt(be=0x00007f98b40c1a90, r=0x00007f98b40da950) + 125 at sql_gencode.c:467
    frame #14: 0x00007f98c3863489 lib_sql.so`backend_dumpstmt(be=0x00007f98b40c1a90, mb=0x00007f98b40c1e70, r=0x00007f98b40da950, top=1, add_end=1) + 219 at sql_gencode.c:488
    frame #15: 0x00007f98c3863ff2 lib_sql.so`backend_dumpproc(be=0x00007f98b40c1a90, c=0x00007f98c3e88328, cq=0x00007f98b411cee0, r=0x00007f98b40da950) + 1246 at sql_gencode.c:637
    frame #16: 0x00007f98c3830297 lib_sql.so`SQLparser(c=0x00007f98c3e88328) + 4602 at sql_scenario.c:1113
    frame #17: 0x00007f98c863ec65 libmonetdb5.so.21`runPhase(c=0x00007f98c3e88328, phase=1) + 122 at mal_scenario.c:517
    frame #18: 0x00007f98c863eda9 libmonetdb5.so.21`runScenarioBody(c=0x00007f98c3e88328) + 288 at mal_scenario.c:550
    frame #19: 0x00007f98c863ef4c libmonetdb5.so.21`runScenario(c=0x00007f98c3e88328) + 76 at mal_scenario.c:579
    frame #20: 0x00007f98c8640a92 libmonetdb5.so.21`MSserveClient(dummy=0x00007f98c3e88328) + 488 at mal_session.c:448
    frame #21: 0x00007f98c864053c libmonetdb5.so.21`MSscheduleClient(command="\xb0\xb9\v\xb4\x98\x7f", challenge="IXs33hCnElR", fin=0x00007f98b4002980, fout=0x00007f98b0002b60) + 3472 at mal_session.c:339
    frame #22: 0x00007f98c86dfe60 libmonetdb5.so.21`doChallenge(data=0x00007f98b00008d0) + 1209 at mal_mapi.c:197
    frame #23: 0x00007f98c8141d36 libbat.so.13`thread_starter(arg=0x00007f98b0004c50) + 68 at gdk_system.c:485
    frame #24: 0x00007f98c58ed454 libpthread.so.0`start_thread + 196
    frame #25: 0x00007f98c562e7df libc.so.6`__GI___clone + 95
(lldb) frame select 4
frame #4: 0x00007f98c384578d lib_sql.so`rel2bin_semijoin(be=0x00007f98b40c1a90, rel=0x00007f98b40d6d90, refs=0x00007f98b40de4e0) + 770 at rel_bin.c:1905
   1902					join = s;
   1903				} else if (s->type != st_join && s->type != st_join2 && s->type != st_joinN) {
   1904					/* handle select expressions */
-> 1905					assert(0);
   1906					return NULL;
   1907				}
   1908				if (s->type == st_join || s->type == st_join2 || s->type == st_joinN) {