Fix the IsSet warning when building the site

layouts/partials/photos/thumbnail.html

@@ -1,3 +1,19 @@
+{{/*
+  Renders a photo thumbnail. If neither a target height or target width are
+  given, and the image is already in the correct orientation, no image
+  processing is performed.
+
+  Arguments
+  ---------
+  "Page" : A reference to the current Page
+  "Height" : The target height of the image
+  "Width" : The target width of the image
+
+  Returns
+  -------
+  The processed thumbnail image resource
+*/}}
+
 {{- $thumbnailResource := .Page.Resources.GetMatch
                             (index .Page.Params "thumbnail" | default "[tT]humbnail*")
                         | default (index (.Page.Resources.ByType "image") 0) -}}
@@ -9,15 +25,15 @@
 {{ $orientation := partial "images/orientation_angle.html" $thumbnailResource }}
 
 {{ $targetWidth := 0 }}
-{{ if isset . "Width" }}
-  {{ $targetWidth = .Width }}
+{{ with .Width }}
+  {{ $targetWidth = . }}
 {{ else }}
   {{ $targetWidth = $thumbnailResource.Width }}
 {{ end }}
 
 {{ $targetHeight := 0 }}
-{{ if isset . "Height" }}
-  {{ $targetHeight = .Height }}
+{{ with .Height }}
+  {{ $targetHeight = . }}
 {{ else }}
   {{ $targetHeight = $thumbnailResource.Height }}
 {{ end }}

layouts/partials/table_of_contents.html

@@ -1,4 +1,4 @@
-{{ if and (gt .WordCount 400) (isset .Params "toc") .Params.toc }}
+{{ if and (gt .WordCount 400) (.Params.toc | default false) }}
 <aside id="table-of-contents">
   <details {{ if eq .Params.toc "open" }}open{{ end }}>
     <summary>Table of Contents</summary>

layouts/photos/atom_entry.atom

@@ -1,4 +1,4 @@
-{{- $thumbnail := partial "photos/thumbnail.html" . -}}
+{{- $thumbnail := partial "photos/thumbnail.html" (dict "Page" . "Width" nil "Height" nil) -}}
 <entry>
   {{ partial "atom_entry_metadata.xml" . }}
   <link rel="enclosure" href="{{ $thumbnail.Permalink }}" type="{{ $thumbnail.MediaType }}" length="{{ len $thumbnail.Content }}" />