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_textprop.vim b/src/testdir/test_textprop.vim
index 5dddd16..d5f67b4 100644
--- a/src/testdir/test_textprop.vim
+++ b/src/testdir/test_textprop.vim
@@ -1214,7 +1214,7 @@
   call assert_fails('call prop_clear(1, 2, [])', 'E715:')
   call assert_fails('call prop_clear(-1, 2)', 'E16:')
   call assert_fails('call prop_find(test_null_dict())', 'E474:')
-  call assert_fails('call prop_find({"bufnr" : []})', 'E158:')
+  call assert_fails('call prop_find({"bufnr" : []})', 'E730:')
   call assert_fails('call prop_find({})', 'E968:')
   call assert_fails('call prop_find({}, "x")', 'E474:')
   call assert_fails('call prop_find({"lnum" : -2})', 'E16:')
@@ -1223,11 +1223,11 @@
   call assert_fails('call prop_remove([])', 'E474:')
   call assert_fails('call prop_remove({}, -2)', 'E16:')
   call assert_fails('call prop_remove({})', 'E968:')
-  call assert_fails('call prop_type_add([], {})', 'E474:')
+  call assert_fails('call prop_type_add([], {})', 'E730:')
   call assert_fails("call prop_type_change('long', {'xyz' : 10})", 'E971:')
-  call assert_fails("call prop_type_delete([])", 'E474:')
+  call assert_fails("call prop_type_delete([])", 'E730:')
   call assert_fails("call prop_type_delete('xyz', [])", 'E715:')
-  call assert_fails("call prop_type_get([])", 'E474:')
+  call assert_fails("call prop_type_get([])", 'E730:')
   call assert_fails("call prop_type_get('', [])", 'E474:')
   call assert_fails("call prop_type_list([])", 'E715:')
 endfunc