Heapster: Prelude.head: empty list crash when invoking heapster_typecheck_mut_funs on empty list

[RyanGlScott]

Given the following C program SAW script:

// test.c

// test.saw
enable_experimental;
env <- heapster_init_env "test" "test.bc";
heapster_typecheck_mut_funs env [];

SAW will crash when attempting to run the program:

$ clang test.c -g -emit-llvm -c
$ ~/Software/saw-1.1/bin/saw test.saw
[12:41:17.884] Loading file "/home/ryanglscott/Documents/Hacking/Haskell/saw-script/test.saw"
[12:41:17.888] Stack trace:
"heapster_typecheck_mut_funs" (/home/ryanglscott/Documents/Hacking/Haskell/saw-script/test.saw:4:1-4:28)
Prelude.head: empty list

Either heapster_typecheck_mut_funs should be altered to accept an empty list, or it should fail with a better error message than Prelude.head: empty list (and the non-empty list requirement should be documented).