patch 8.2.3225: incsearch highlighting is attempted halfway a mapping

Problem:    Incsearch highlighting is attempted halfway a mapping.
Solution:   Only do incsearch highlighting if keys were typed or there is no
            more typeahead.
diff --git a/src/ex_getln.c b/src/ex_getln.c
index 22f1cf6..40b8886 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -2390,7 +2390,7 @@
 	    trigger_cmd_autocmd(cmdline_type, EVENT_CMDLINECHANGED);
 
 #ifdef FEAT_SEARCH_EXTRA
-	if (xpc.xp_context == EXPAND_NOTHING)
+	if (xpc.xp_context == EXPAND_NOTHING && (KeyTyped || vpeekc() == NUL))
 	    may_do_incsearch_highlighting(firstc, count, &is_state);
 #endif