Handle blobs GitHub cannot preview

Binary files with no preview (a .ttf, say) have no rawLines, no
colorizedLines and no richText, so the blob view's final branch threw on
a null textLines and the page 500ed. Offer the raw file instead.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

3 files changed, 44 insertions, 2 deletions

diff --git a/cgithub/src/app.test.ts b/cgithub/src/app.test.ts
index 59ed352..94bf205 100644
--- a/cgithub/src/app.test.ts
+++ b/cgithub/src/app.test.ts
@@ -92,6 +92,28 @@ describe("sidebar fragment", () => {
   });
 });
 
+describe("blob view", () => {
+  const blob = {
+    repo: { owner: "justrajdeep", name: "fonts" },
+    branch: "master",
+    path: "Times New Roman.ttf",
+    language: null,
+    size: "815 KB",
+    image: false,
+    textLines: null,
+    htmlLines: null,
+    htmlContent: null,
+  };
+
+  // GitHub previews neither the text nor the bytes of most binary files.
+  it("should offer the raw file when there is nothing to display", () => {
+    const html = eta.render("blob.eta", blob);
+
+    assert.match(html, /This file cannot be displayed\./);
+    assert.match(html, /href="\/justrajdeep\/fonts\/raw\/master\/Times New Roman.ttf">View raw/);
+  });
+});
+
 describe("redirects to GitHub", () => {
   // An HTTP redirect would be caught by the extension's declarativeNetRequest
   // rules and bounced straight back here.
diff --git a/cgithub/src/scraper.test.ts b/cgithub/src/scraper.test.ts
index 24fdfc0..836235e 100644
--- a/cgithub/src/scraper.test.ts
+++ b/cgithub/src/scraper.test.ts
@@ -332,6 +332,24 @@ describe("GitHub scraper", () => {
       assert.strictEqual(data.htmlLines, null);
       assert.strictEqual(data.htmlContent, null);
     });
+
+    // A binary file GitHub has no preview for: no content of any kind, and the
+    // path exercises escaping of a space.
+    it("should support an unpreviewable binary file", async () => {
+      const data = await getGitHubBlob("justrajdeep", "fonts", "master", "Times New Roman.ttf");
+
+      assert.strictEqual(data.repo.owner, "justrajdeep");
+      assert.strictEqual(data.repo.name, "fonts");
+      assert.strictEqual(data.branch, "master");
+      assert.strictEqual(data.path, "Times New Roman.ttf");
+
+      assert.strictEqual(data.size, "815 KB");
+      assert.strictEqual(data.language, null);
+      assert.strictEqual(data.image, false);
+      assert.strictEqual(data.textLines, null);
+      assert.strictEqual(data.htmlLines, null);
+      assert.strictEqual(data.htmlContent, null);
+    });
   });
 
   describe("owner pages", () => {
diff --git a/cgithub/views/blob.eta b/cgithub/views/blob.eta
index ed1e84b..c7315f6 100644
--- a/cgithub/views/blob.eta
+++ b/cgithub/views/blob.eta
@@ -8,7 +8,7 @@
   <% } %>
   <div><%= it.size %></div>
   <div>
-    <a href="/<%= it.repo.owner %>/<%= it.repo.name %>/raw/<%= it.branch %>/<%= it.path %>">Raw</a>
+    <a href="/<%= it.repo.owner %>/<%= it.repo.name %>/raw/<%= it.branch %>/<%= it.path %>">View raw</a>
   </div>
 </div>
 
@@ -18,6 +18,8 @@
   <div class="box"><%~ it.htmlContent %></div>
 <% } else if (it.htmlLines) { %>
   <pre class="box"><code><%~ it.htmlLines.join("\n") %></code></pre>
-<% } else { %>
+<% } else if (it.textLines) { %>
   <pre class="box"><code><%= it.textLines.join("\n") %></code></pre>
+<% } else { %>
+  <div class="box">This file cannot be displayed</div>
 <% } %>