patch 8.2.0502: Vim9: some code is not tested

Problem:    Vim9: some code is not tested.
Solution:   Add more tests.  Fix uncovered problems.
diff --git a/src/search.c b/src/search.c
index 2005b79..95a27f8 100644
--- a/src/search.c
+++ b/src/search.c
@@ -1312,7 +1312,7 @@
 	     * If there is a matching '/' or '?', toss it.
 	     */
 	    ps = strcopy;
-	    p = skip_regexp(pat, search_delim, (int)p_magic, &strcopy);
+	    p = skip_regexp_ex(pat, search_delim, (int)p_magic, &strcopy, NULL);
 	    if (strcopy != ps)
 	    {
 		// made a copy of "pat" to change "\?" to "?"