fix(decoration): fix crash when on_lines decor provider modifies marktree

If a "on_lines" callback changes the structure of the marktree, the
iterator (which is used for an entire window viewport) might now
point to invalid memory. Restore the iterator to the beginning of the
line in this case.

fixes #29484

1 files changed, 3 insertions, 3 deletions

diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index 3062b0f2a3..d5273ff3d1 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -1051,12 +1051,12 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, int col_rows, s
       }
     }
 
-    has_decor = decor_redraw_line(wp, lnum - 1, &decor_state);
-
     if (!end_fill) {
-      decor_providers_invoke_line(wp, lnum - 1, &has_decor);
+      decor_providers_invoke_line(wp, lnum - 1);
     }
 
+    has_decor = decor_redraw_line(wp, lnum - 1, &decor_state);
+
     if (has_decor) {
       extra_check = true;
     }