patch 8.2.1183: assert_fails() checks the last error message

Problem:    assert_fails() checks the last error message.
Solution:   Check the first error, it is more relevant.  Fix all the tests
            that rely on the old behavior.
diff --git a/src/testdir/test_writefile.vim b/src/testdir/test_writefile.vim
index 9106f86..5c9e4b1 100644
--- a/src/testdir/test_writefile.vim
+++ b/src/testdir/test_writefile.vim
@@ -310,7 +310,7 @@
     autocmd BufWritePre Xfile enew | write
   augroup END
   e Xfile
-  call assert_fails('lockmarks write', 'E203:')
+  call assert_fails('lockmarks write', ['E32', 'E203:'])
   augroup WriteTest
     au!
   augroup END