#528: hotfix for search, until we find a reason

assets/search-data.json

 [
 {{- $pages := where .Site.Pages "Kind" "in" (slice "page" "section") -}}
 {{- $pages = where $pages "Params.booksearchexclude" "!=" true -}}
-{{- $pages = where $pages "Content" "not in" (slice nil "") -}}
+{{/* Remove until we know why it does not work, see https://github.com/alex-shpak/hugo-book/issues/528 */}}
+{{/*- $pages = where $pages "Content" "not in" (slice nil "") -*/}}
+{{- $pages = where $pages "Content" "!=" "" -}}
 
 {{ range $index, $page := $pages }}
 {{ if gt $index 0}},{{end}} {