Fails on input with no clauses, or when preprocessing results in no remaining clauses.

[agreatnate]

When running on the .cnf file:
p cnf 1 0

the program fails with

sharpSAT: .../sharpSAT/include/sharpSAT/unions.h:135: T sharpSAT::DebugVariant::get() const [with T = sharpSAT::VariableIndex; Ts = {sharpSAT::ClauseIndex, sharpSAT::VariableIndex}]: Assertion `(type_id == variant_find_type<0,T,Ts...>()) && "Variant was written a different type than is being read."' failed.

The same error occurs on a slightly more interesting file like
p cnf 3 3
-1 0
-2 0
-2 -3 0