Give friendly error on empty backlog repo (#1294)

Currently you get a complicated error about a nil dereference. This
makes it clear what happened.

Author: illicitonion

common-theme/layouts/_default/backlog.html

@@ -14,7 +14,7 @@
       for each repo, grab the issues that match the filter
     */}}
     {{ range $repos }}
-      {{ $issueBlocks := partial "block/issues-list-as-blocks.html" (dict "backlog" . "backlog_filter" $backlog_filter) }}
+      {{ $issueBlocks := partial "block/issues-list-as-blocks.html" (dict "backlog" . "backlog_filter" $backlog_filter "path" $currentPath) }}
       {{ $repo := . }}    
       {{ range $issueBlocks }}
         <div class="c-alert" role="alert" hidden>

common-theme/layouts/_default/success.html

@@ -28,13 +28,26 @@ <h2 class="e-heading__4 c-objectives__title is-invisible">
           {{ $prep := .Site.GetPage (printf "%sprep/index.md"
             .CurrentSection.RelPermalink)
           }}
-          {{ $backlog := .Site.GetPage (printf "%sbacklog/index.md"
+          {{ $backlogPage := .Site.GetPage (printf "%sbacklog/index.md"
             .CurrentSection.RelPermalink)
           }}
           {{ $dayplan := .Site.GetPage (printf "%sday-plan/index.md"
             .CurrentSection.RelPermalink)
           }}
-          {{ $issueBlocks := partial "block/issues-list-as-blocks.html" (dict "backlog" $backlog.Params.backlog "backlog_filter" $backlog.Params.backlog_filter) }}
+          {{ $issueBlocks := slice }}
+          {{ if $backlogPage }}
+            {{ $backlogs := $backlogPage.Params.backlog }}
+            {{ if $backlogs }}
+              {{ if reflect.IsSlice $backlogs }}
+                {{ range $backlogs }}
+                  {{ $issueBlocks = append (partial "block/issues-list-as-blocks.html" (dict "backlog" . "backlog_filter" $backlogPage.Params.backlog_filter "path" $pageContext.Path)) $issueBlocks }}
+                {{ end }}
+              {{ else }}
+                {{ $backlog := $backlogs }}
+                {{ $issueBlocks = append (partial "block/issues-list-as-blocks.html" (dict "backlog" $backlog "backlog_filter" $backlogPage.Params.backlog_filter "path" $pageContext.Path)) $issueBlocks }}
+              {{ end }}
+            {{ end }}
+          {{ end }}
           {{ $blocks := slice }}
           {{/* append non-nil blocks */}}
           {{ range $prep.Params.blocks }}

common-theme/layouts/partials/block/issues-list-as-blocks.html

@@ -11,6 +11,7 @@
   "owner" site.Params.owner
   "repo" .backlog
 }}
+{{ $currentPath := .path }}
 {{ if .backlog_filter }}
   {{ $variables = merge $variables (dict "labels" .backlog_filter) }}
 {{ end }}
@@ -53,9 +54,13 @@
 {{ $issueBlocks := slice }}
 {{ with resources.GetRemote "https://api.github.com/graphql" (merge $request (partial "github-auth.html" .)) }}
   {{ with .Content | unmarshal }}
-    {{ with .data.repository.issues.nodes }}
-      {{ range sort . "title" "asc" }}
-        {{ $issueBlocks = $issueBlocks | append (dict "name" .title "src" .url "number" .number "labels" .labels) }}
+    {{ if not .data.repository }}
+      {{ errorf "GitHub repository %s/%s referenced on %s had no issues" site.Params.owner (index $variables "repo") $currentPath }}
+    {{ else }}
+      {{ with .data.repository.issues.nodes }}
+        {{ range sort . "title" "asc" }}
+          {{ $issueBlocks = $issueBlocks | append (dict "name" .title "src" .url "number" .number "labels" .labels) }}
+        {{ end }}
       {{ end }}
     {{ end }}
   {{ end }}