patch 8.2.2743: Vim9: function state stuck when compiling with ":silent!"

Problem:    Vim9: function state stuck when compiling with ":silent!".
Solution:   Check for uf_def_status to be UF_COMPILING.
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 6a3dfbb..e254f44 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -2603,6 +2603,20 @@
 
   # Second call won't try compiling again
   assert_fails('call g:Broken()', 'E1091: Function is not compiled: Broken')
+  delfunc g:Broken
+
+  # No error when compiling with :silent!
+  lines =<< trim END
+    def g:Broken()
+      echo 'a' + []
+    enddef
+    silent! defcompile
+  END
+  CheckScriptSuccess(lines)
+
+  # Calling the function won't try compiling again
+  assert_fails('call g:Broken()', 'E1091: Function is not compiled: Broken')
+  delfunc g:Broken
 enddef