[Bug] Segfault upon incorrect assginment in function call

[joshichaitanya3]

Describe the bug
A typo in the constructor for FloryHuggins results in a segfault

To Reproduce

var m = Mesh("tetrahedron.mesh") // Can be found under test/functionals/floryhuggins

var mref = m.clone()

var lfh = FloryHuggins(mref. // This "." should be a ","
    a = 1.0,
    b = 1.0,
    c = 1.0,
    phi0=0.5
)

print lfh

Expected behavior
Some error indicating that the period is incorrect

[ConduitDan]

This segfaults in program_bindobject in vm/vim.c:100 obj it in invalid pointer
We should probably catch this as a parse error before this happens as mref. is not valid.

[ConduitDan]

Assignment in fn call