patch 8.2.5072: using uninitialized value and freed memory in spell command

Problem:    Using uninitialized value and freed memory in spell command.
Solution:   Initialize "attr".  Check for empty line early.

src/testdir/test_spell_utf8.vim

@@ -802,5 +802,20 @@ func Test_word_index()
   call delete('Xtmpfile')
 endfunc
 
+func Test_check_empty_line()
+  " This was using freed memory
+  enew
+  spellgood! fl
+  norm z=
+  norm yy
+  sil! norm P]svc
+  norm P]s
+
+  " set 'encoding' to clear the wordt list
+  set enc=latin1
+  set enc=utf-8
+  bwipe!
+endfunc
+
 
 " vim: shiftwidth=2 sts=2 expandtab