patch 9.0.0828: various typos

Problem:    Various typos.
Solution:   Correct typos. (closes #11432)
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 58e214c..ac86512 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -4366,7 +4366,7 @@
   g:StopVimInTerminal(buf)
 enddef
 
-def Test_ambigous_command_error()
+def Test_ambiguous_command_error()
   var lines =<< trim END
       vim9script
       command CmdA echomsg 'CmdA'