Fix warnings: eval.c: set_var_lval(): Np dereference: FP.

Problem    : Dereference of null pointer @ 2273.
Diagnostic : False positive.
Rationale  : Suggested error would happen when assigning an rvalue with
             more items than the lvalue. Then we would enter conditional
             at:
             ```
             if (lp->ll_li->li_next == NULL) {
               /* Need to add an empty item. */
               list_append_number(lp->ll_list, 0);
             }
             lp->ll_li = lp->ll_li->li_next;
             ```
             Analyzer thinks the value assigned to lp->ll_li is still
             NULL and is hit on the next iteration.
Resolution : Assert lp->ll_li->li_next is not null anymore after
             list_append_number().

1 files changed, 1 insertions, 0 deletions

diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 498795dc38..d7f820ae78 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -2272,6 +2272,7 @@ static void set_var_lval(lval_T *lp, char_u *endp, typval_T *rettv, int copy, ch
       if (lp->ll_li->li_next == NULL) {
         /* Need to add an empty item. */
         list_append_number(lp->ll_list, 0);
+        assert(lp->ll_li->li_next);
       }
       lp->ll_li = lp->ll_li->li_next;
       ++lp->ll_n1;