patch 9.0.0228: crash when pattern looks below the last line

Problem:    Crash when pattern looks below the last line.
Solution:   Consider invalid lines to be empty. (closes #10938)
diff --git a/src/testdir/test_regexp_latin.vim b/src/testdir/test_regexp_latin.vim
index 1ba7d17..bc08439 100644
--- a/src/testdir/test_regexp_latin.vim
+++ b/src/testdir/test_regexp_latin.vim
@@ -1129,4 +1129,16 @@
   delfunc Repl
 endfunc
 
+def Test_compare_columns()
+  # this was using a line below the last line
+  enew
+  setline(1, ['', ''])
+  prop_type_add('name', {highlight: 'ErrorMsg'})
+  prop_add(1, 1, {length: 1, type: 'name'})
+  search('\%#=1\%>.l\n.*\%<2v', 'nW')
+  search('\%#=2\%>.l\n.*\%<2v', 'nW')
+  bwipe!
+  prop_type_delete('name')
+enddef
+
 " vim: shiftwidth=2 sts=2 expandtab