patch 8.2.2223: Vim9: Reloading marks a :def function as deleted

Problem:    Vim9: Reloading marks a :def function as deleted.
Solution:   Clear the function contents but keep the index.
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index cdd83c3..c88420d 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -1174,10 +1174,7 @@
     var s:notReloaded = 'yes'
     s:reloaded = 'first'
     def g:Values(): list<string>
-      return [s:reloaded, s:notReloaded, Once()]
-    enddef
-    def g:CallAgain(): string
-      return Again()
+      return [s:reloaded, s:notReloaded, Again(), Once()]
     enddef
 
     def Once(): string
@@ -1188,20 +1185,16 @@
   g:loadCount = 0
   source XReloaded
   assert_equal(1, g:loadCount)
-  assert_equal(['first', 'yes', 'once'], g:Values())
-  assert_equal('again', g:CallAgain())
+  assert_equal(['first', 'yes', 'again', 'once'], g:Values())
   source XReloaded
   assert_equal(2, g:loadCount)
-  assert_equal(['init', 'yes', 'once'], g:Values())
-  assert_fails('call g:CallAgain()', 'E933:')
+  assert_equal(['init', 'yes', 'again', 'once'], g:Values())
   source XReloaded
   assert_equal(3, g:loadCount)
-  assert_equal(['init', 'yes', 'once'], g:Values())
-  assert_fails('call g:CallAgain()', 'E933:')
+  assert_equal(['init', 'yes', 'again', 'once'], g:Values())
 
   delete('Xreloaded')
   delfunc g:Values
-  delfunc g:CallAgain
   unlet g:loadCount
 enddef