feat(nuldoc): improve error handling when a tag is undefined

4 files changed, 15 insertions, 17 deletions

diff --git a/nuldoc-src/config.ts b/nuldoc-src/config.ts
index cbbabca..76a05fe 100644
--- a/nuldoc-src/config.ts
+++ b/nuldoc-src/config.ts
@@ -33,3 +33,10 @@ export const config = {
 };
 
 export type Config = typeof config;
+
+export function getTagLabel(c: Config, slug: string): string {
+  if (!(slug in c.blog.tagLabels)) {
+    throw new Error(`Unknown tag: ${slug}`);
+  }
+  return (c.blog.tagLabels as { [slug: string]: string })[slug];
+}
diff --git a/nuldoc-src/pages/post.ts b/nuldoc-src/pages/post.ts
index d870e99..24a6d5f 100644
--- a/nuldoc-src/pages/post.ts
+++ b/nuldoc-src/pages/post.ts
@@ -2,7 +2,7 @@ import { join } from "std/path/mod.ts";
 import { globalFooter } from "../components/global_footer.ts";
 import { globalHeader } from "../components/global_header.ts";
 import { pageLayout } from "../components/page_layout.ts";
-import { Config } from "../config.ts";
+import { Config, getTagLabel } from "../config.ts";
 import { el, Element, text } from "../dom.ts";
 import { Document } from "../docbook/document.ts";
 import { Page } from "../page.ts";
@@ -57,9 +57,7 @@ export async function generatePostPage(
                     "a",
                     [["href", `/tags/${slug}/`]],
                     text(
-                      (config.blog.tagLabels as {
-                        [key: string]: string;
-                      })[slug],
+                      getTagLabel(config, slug),
                     ),
                   ),
                 )
@@ -115,9 +113,7 @@ export async function generatePostPage(
     {
       metaCopyrightYear: getPostCreatedDate(doc).year,
       metaDescription: doc.summary,
-      metaKeywords: doc.tags.map((slug) =>
-        (config.blog.tagLabels as { [key: string]: string })[slug]
-      ),
+      metaKeywords: doc.tags.map((slug) => getTagLabel(config, slug)),
       metaTitle: `${doc.title} | ${config.blog.siteName}`,
       requiresSyntaxHighlight: true,
     },
diff --git a/nuldoc-src/pages/slide.ts b/nuldoc-src/pages/slide.ts
index e5f40a0..a75aeb6 100644
--- a/nuldoc-src/pages/slide.ts
+++ b/nuldoc-src/pages/slide.ts
@@ -3,7 +3,7 @@ import { globalFooter } from "../components/global_footer.ts";
 import { globalHeader } from "../components/global_header.ts";
 import { pageLayout } from "../components/page_layout.ts";
 import { staticScriptElement } from "../components/utils.ts";
-import { Config } from "../config.ts";
+import { Config, getTagLabel } from "../config.ts";
 import { el, text } from "../dom.ts";
 import { Page } from "../page.ts";
 import { dateToString, Revision } from "../revision.ts";
@@ -53,9 +53,7 @@ export async function generateSlidePage(
                     "a",
                     [["href", `/tags/${slug}/`]],
                     text(
-                      (config.blog.tagLabels as {
-                        [key: string]: string;
-                      })[slug],
+                      getTagLabel(config, slug),
                     ),
                   ),
                 )
@@ -113,9 +111,7 @@ export async function generateSlidePage(
     {
       metaCopyrightYear: getPostCreatedDate(slide).year,
       metaDescription: slide.title,
-      metaKeywords: slide.tags.map((slug) =>
-        (config.blog.tagLabels as { [key: string]: string })[slug]
-      ),
+      metaKeywords: slide.tags.map((slug) => getTagLabel(config, slug)),
       metaTitle: `${slide.event} (${slide.talkType}) | ${config.blog.siteName}`,
       requiresSyntaxHighlight: true,
     },
diff --git a/nuldoc-src/pages/tag.ts b/nuldoc-src/pages/tag.ts
index cb60d21..f501cb3 100644
--- a/nuldoc-src/pages/tag.ts
+++ b/nuldoc-src/pages/tag.ts
@@ -3,7 +3,7 @@ import { globalHeader } from "../components/global_header.ts";
 import { pageLayout } from "../components/page_layout.ts";
 import { postPageEntry } from "../components/post_page_entry.ts";
 import { slidePageEntry } from "../components/slide_page_entry.ts";
-import { Config } from "../config.ts";
+import { Config, getTagLabel } from "../config.ts";
 import { el, text } from "../dom.ts";
 import { Page } from "../page.ts";
 import { getPostCreatedDate } from "./post.ts";
@@ -19,8 +19,7 @@ export async function generateTagPage(
   pages: TaggedPage[],
   config: Config,
 ): Promise<TagPage> {
-  const tagLabel =
-    (config.blog.tagLabels as { [key: string]: string })[tagSlug];
+  const tagLabel = getTagLabel(config, tagSlug);
   const pageTitle = `タグ「${tagLabel}」一覧`;
 
   const body = el(