Handle the 404 case when viewing store items

guix-data-service/web/controller.scm

@@ -507,7 +507,11 @@
   (let ((derivation (select-derivation-by-output-filename conn filename)))
     (match derivation
       (()
-       #f)
+       (render-html
+        #:sxml (general-not-found
+                "Store item not found"
+                "No derivation found producing this output")
+        #:code 404))
       (derivations
        (render-html
         #:sxml (view-store-item filename

guix-data-service/web/view/html.scm

@@ -29,6 +29,7 @@
   #:use-module (texinfo html)
   #:use-module (json)
   #:export (index
+            general-not-found
             unknown-revision
             view-statistics
             view-revision-package-and-version
@@ -1389,6 +1390,15 @@
                      (take data 2))
                    (vlist->list target-packages-vhash))))))))))))
 
+(define (general-not-found header-text body)
+  (layout
+   #:body
+   `(,(header)
+     (div
+      (@ (class "container"))
+      (h1 ,header-text)
+      (p ,body)))))
+
 (define (unknown-revision commit-hash job)
   (layout
    #:body