Handle package versions not being found

guix-data-service/web/revision/controller.scm

@@ -993,6 +993,12 @@
            '(application/json text/html)
            mime-types)
       ((application/json)
+       (if (null? metadata)
+           (render-json
+            `((name . ,name)
+              (version . ,version)
+              (error . "package not found"))
+            #:code 404)
            (render-json
             `((name . ,name)
               (version . ,version)
@@ -1014,7 +1020,7 @@
                                          (derivation . ,file-name)
                                          (outputs . ,(list->vector outputs)))))
                                     derivations))))
-        #:extra-headers http-headers-for-unchanging-content))
+            #:extra-headers http-headers-for-unchanging-content)))
       (else
        (render-html
         #:sxml (view-revision-package-and-version commit-hash
@@ -1030,6 +1036,9 @@
                                                   #:header-link header-link
                                                   #:version-history-link
                                                   version-history-link)
+        #:code (if (null? metadata)
+                   404
+                   200)
         #:extra-headers http-headers-for-unchanging-content)))))
 
 (define* (render-revision-package-derivations mime-types

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

@@ -243,6 +243,8 @@
        (div
         (@ (class "col-sm-12"))
         ,(match package-metadata
+           (()
+            "Package not found at this version")
            (((synopsis synopsis-locale description description-locale home-page file line column-number
                        licenses))
             `(dl