patch 8.2.4654: missing changes for import check

Problem:    Missing changes for import check.
Solution:   Add missing changes.
diff --git a/src/vim9script.c b/src/vim9script.c
index 0dad36f..a63f2f7 100644
--- a/src/vim9script.c
+++ b/src/vim9script.c
@@ -399,7 +399,14 @@
 	{
 	    int error = OK;
 
-	    // script does not exist yet, create a new scriptitem
+	    // Script does not exist yet, check name and create a new
+	    // scriptitem.
+	    if (!file_is_readable(fname))
+	    {
+		semsg(_(mch_isdir(fname) ? e_str_is_directory
+					  : e_cannot_read_from_str_2), fname);
+		return FAIL;
+	    }
 	    *sid = get_new_scriptitem_for_fname(&error, fname);
 	    if (error == FAIL)
 		return FAIL;