hugolib: Change to output non-panic error message if missing shortcode template

A panic occurred when the `nested` variable was nil.
Changed to check if the `nested` variable is nil.

Fixes #6075

diff --git a/hugolib/shortcode.go b/hugolib/shortcode.go
index 895d0dcf2d8b93df3d8cb2523e58387733ecf33d..8323962c0c7b29980e228fcff7b95e9ef6bcdede 100644 (file)
--- a/hugolib/shortcode.go
+++ b/hugolib/shortcode.go
@@ -473,9 +473,10 @@ Loop:
                                pt.Backup()
                                nested, err := s.extractShortcode(nestedOrdinal, nextLevel, pt)
                                nestedOrdinal++
-                               if nested.name != "" {
+                               if nested != nil && nested.name != "" {
                                        s.nameSet[nested.name] = true
                                }
+
                                if err == nil {
                                        sc.inner = append(sc.inner, nested)
                                } else {