patch 8.2.3783: confusing error for using a variable as a function

Problem:    Confusing error for using a variable as a function.
Solution:   If a function is not found but there is a variable, give a more
            useful error. (issue #9310)
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 7365fd8..2c871d3 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -1459,7 +1459,7 @@
 def Test_call_funcref()
   g:SomeFunc('abc')->assert_equal(3)
   assert_fails('NotAFunc()', 'E117:', '', 2, 'Test_call_funcref') # comment after call
-  assert_fails('g:NotAFunc()', 'E117:', '', 3, 'Test_call_funcref')
+  assert_fails('g:NotAFunc()', 'E1085:', '', 3, 'Test_call_funcref')
 
   var lines =<< trim END
     vim9script