patch 8.2.3970: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more errors to errors.h.
diff --git a/src/window.c b/src/window.c
index 51055b4..3784368 100644
--- a/src/window.c
+++ b/src/window.c
@@ -2496,7 +2496,7 @@
 	return FAIL; // window is already being closed
     if (win_unlisted(win))
     {
-	emsg(_(e_autocmd_close));
+	emsg(_(e_cannot_close_autocmd_or_popup_window));
 	return FAIL;
     }
     if ((firstwin == aucmd_win || lastwin == aucmd_win) && one_window())