ponyc: Segfault in 'Simplify the CFG' pass with Pony 0.22.6

Got a segfault compiling my hobby project on Arch Linux x86_64: https://bitbucket.org/bytefu/funky/src/simplify-cfg-fail/

$ ponyc
Building builtin -> /usr/lib/pony/0.22.6/packages/builtin
Building . -> /home/burjui/Devel/funky
Building libfunky -> /home/burjui/Devel/funky/libfunky
Building files -> /usr/lib/pony/0.22.6/packages/files
Building time -> /usr/lib/pony/0.22.6/packages/time
Building collections -> /usr/lib/pony/0.22.6/packages/collections
Building ponytest -> /usr/lib/pony/0.22.6/packages/ponytest
Building buffered -> /usr/lib/pony/0.22.6/packages/buffered
Building term -> /usr/lib/pony/0.22.6/packages/term
Building promises -> /usr/lib/pony/0.22.6/packages/promises
Building strings -> /usr/lib/pony/0.22.6/packages/strings
Building signals -> /usr/lib/pony/0.22.6/packages/signals
Building capsicum -> /usr/lib/pony/0.22.6/packages/capsicum
Building format -> /usr/lib/pony/0.22.6/packages/format
Building itertools -> /usr/lib/pony/0.22.6/packages/itertools
Building libfunky/ast -> /home/burjui/Devel/funky/libfunky/ast
Generating
 Reachability
 Selector painting
 Data prototypes
 Data types
 Function prototypes
 Functions
 Descriptors
Optimising
Stack dump:
0.      Running pass 'Simplify the CFG' on function '@Main_val_process_ooo'
[1]    9226 segmentation fault (core dumped)  ponyc

Though the segfault goes away after uncommenting the line 66 in main.pony:

token_count = token_count + 1

GDB shows the following stacktrace:

#0  0x00007ffff4f747c4 in llvm::removeUnreachableBlocks(llvm::Function&, llvm::LazyValueInfo*) () from /usr/lib/libLLVM-6.0.so
#1  0x00007ffff5376dab in ?? () from /usr/lib/libLLVM-6.0.so
#2  0x00007ffff47efdc1 in llvm::FPPassManager::runOnFunction(llvm::Function&) ()
   from /usr/lib/libLLVM-6.0.so
#3  0x00007ffff47efebd in llvm::legacy::FunctionPassManagerImpl::run(llvm::Function&)
    () from /usr/lib/libLLVM-6.0.so
#4  0x00007ffff47f0405 in llvm::legacy::FunctionPassManager::run(llvm::Function&) ()
   from /usr/lib/libLLVM-6.0.so
#5  0x00005555555fc8b4 in optimise(compile_t*, bool) ()
#6  0x00005555555fca40 in genopt ()
#7  0x000055555560b031 in genexe ()
#8  0x000055555559a96e in codegen ()
#9  0x0000555555579be7 in compile_package ()
#10 0x000055555557978d in main ()