Security fixes

src/main.c

@@ -169,6 +169,9 @@ intptr_t systemCalls(vm_t* vm, intptr_t* args)
 
     default:
         fprintf(stderr, "Bad system call: %i\n", id);
+        vm->lastError = VM_PC_OUT_OF_RANGE;
+        Com_Error(vm->lastError, "VM pc out of range");
+        return -1;
     }
     return 0;
 }

src/vm/vm.c

@@ -871,7 +871,7 @@ locals from sp
 static int VM_CallInterpreted(vm_t* vm, int* args)
 {
     uint8_t  stack[OPSTACK_SIZE + 15];
-    int*     opStack;
+    int*     opStack = 0;
     uint8_t  opStackOfs;
     int      programCounter;
     int      programStack;