fix(coverity/530826): validate_opt_idx unchecked negative idx (#32081)

Problem:
opt_idx possible negative value used as index

Solution:
check opt_idx not less than zero (kOptInvalid)

1 files changed, 3 insertions, 3 deletions

diff --git a/src/nvim/option.c b/src/nvim/option.c
index 073a816d0c..f9eb67ff83 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -980,12 +980,12 @@ static int validate_opt_idx(win_T *win, OptIndex opt_idx, int opt_flags, uint32_
 
   // Skip all options that are not window-local (used when showing
   // an already loaded buffer in a window).
-  if ((opt_flags & OPT_WINONLY) && (opt_idx == kOptInvalid || !option_is_window_local(opt_idx))) {
+  if ((opt_flags & OPT_WINONLY) && !option_is_window_local(opt_idx)) {
     return FAIL;
   }
 
   // Skip all options that are window-local (used for :vimgrep).
-  if ((opt_flags & OPT_NOWIN) && opt_idx != kOptInvalid && option_is_window_local(opt_idx)) {
+  if ((opt_flags & OPT_NOWIN) && option_is_window_local(opt_idx)) {
     return FAIL;
   }
 
@@ -3267,7 +3267,7 @@ bool is_option_hidden(OptIndex opt_idx)
 /// Check if option supports a specific type.
 bool option_has_type(OptIndex opt_idx, OptValType type)
 {
-  return options[opt_idx].type == type;
+  return opt_idx != kOptInvalid && options[opt_idx].type == type;
 }
 
 /// Check if option supports a specific scope.