Invariant check fails with "elaborate_symbol_rec" error

[ShashankVM]

Project:
https://github.com/ShashankVM/arbiter_bmc

Command used on latest ebmc cloned from GitHub today:
ebmc -top top.sv *sv

Output:

Parsing bsg_arb_round_robin.sv
Parsing bsg_defines.sv
Parsing bsg_scan.sv
Parsing top.sv
Converting
Type-checking Verilog::bsg_scan
Making bsg_scan.o a wire
--- begin invariant violation report ---
Invariant check failed
File: verilog_typecheck_expr.h:128 function: elaborate_symbol_rec
Condition: false
Reason: Precondition
Backtrace:
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x1bf3d3) [0x58902a3e53d3]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x1c04f3) [0x58902a3e64f3]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0xe2572) [0x58902a308572]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x498cfd) [0x58902a6becfd]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x4b4fa2) [0x58902a6dafa2]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x4b523b) [0x58902a6db23b]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x4b4198) [0x58902a6da198]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x48b0dc) [0x58902a6b10dc]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x48b8dc) [0x58902a6b18dc]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x48b7ff) [0x58902a6b17ff]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x48b7ff) [0x58902a6b17ff]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x48bdb4) [0x58902a6b1db4]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x48f1fe) [0x58902a6b51fe]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x48981d) [0x58902a6af81d]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x4919b7) [0x58902a6b79b7]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x494219) [0x58902a6ba219]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x4983be) [0x58902a6be3be]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x56ad72) [0x58902a790d72]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x48200c) [0x58902a6a800c]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x46420a) [0x58902a68a20a]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x10d0b5) [0x58902a3330b5]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x10d025) [0x58902a333025]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x10dfd5) [0x58902a333fd5]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0xfa599) [0x58902a320599]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0xfb3c1) [0x58902a3213c1]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0x10ffb8) [0x58902a335fb8]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0xd5fbb) [0x58902a2fbfbb]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0xd4728) [0x58902a2fa728]
/lib/x86_64-linux-gnu/libc.so.6(+0x2a1ca) [0x77916b62a1ca]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x8b) [0x77916b62a28b]
/home/shashank/arbiter_bmc/hw-cbmc/src/ebmc/ebmc(+0xdc905) [0x58902a302905]


--- end invariant violation report ---
Aborted (core dumped)

[ShashankVM]

It looks like it's due to using an undeclared signal. The arbiter-bmc project is a work in progress. I'll see if declaring the signal helps.