patch 9.0.2134: ml_get error when scrollingv9.0.2134

Problem:  ml_get error when scrolling after delete
Solution: mark topline to be validated in main_loop
          if it is larger than current buffers line
          count

reset_lnums() is called after e.g. TextChanged autocommands and it may
accidentally cause curwin->w_topline to become invalid, e.g. if the
autocommand has deleted some lines.

So verify that curwin->w_topline points to a valid line and if not, mark
the window to have w_topline recalculated in main_loop() in
update_topline() after reset_lnums() returns.

fixes: #13568
fixes: #13578

Signed-off-by: Christian Brabandt <cb@256bit.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/src/testdir/dumps/Test_delete_ml_get_errors_1.dump b/src/testdir/dumps/Test_delete_ml_get_errors_1.dump
new file mode 100644
index 0000000000..9a332a6b9b
--- /dev/null
+++ b/src/testdir/dumps/Test_delete_ml_get_errors_1.dump
@@ -0,0 +1,10 @@
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