Compiler crash via unchecked parser null pointer

NULL pointer dereference in the MiniZinc parser before 2.8.0 allows local users to crash the compiler with a crafted .mzn file. The ti_expr parser path uses a null pointer before it can throw the intended syntax error for malformed model input. Exploitation requires a local user to invoke the compiler on an attacker-controlled model; the dispute concerns the absence of a common unattended processing use case.