[gtksourceview/wip/chergert/vim] fix k at top line

[Christian Hergert <chergert src gnome org>]

commit 5a22d3086bd6b42ed9c13d34e229ff7b59bafd8c
Author: Christian Hergert <chergert redhat com>
Date:   Sun Nov 7 11:01:28 2021 -0800

    fix k at top line

 gtksourceview/vim/gtk-source-vim-motion.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/gtksourceview/vim/gtk-source-vim-motion.c b/gtksourceview/vim/gtk-source-vim-motion.c
index ba3e4d6e..0eae6609 100644
--- a/gtksourceview/vim/gtk-source-vim-motion.c
+++ b/gtksourceview/vim/gtk-source-vim-motion.c
@@ -653,7 +653,8 @@ motion_prev_line_visual_column (GtkTextIter        *iter,
        if (self->apply_count != 1 || count == 0)
                return FALSE;
 
-       gtk_text_buffer_get_iter_at_line (buffer, iter, line - count);
+       line = count > line ? 0 : line - count;
+       gtk_text_buffer_get_iter_at_line (buffer, iter, line);
        get_iter_at_visual_column (view, iter, column);
 
        if (!gtk_text_iter_starts_line (iter) && gtk_text_iter_ends_line (iter))