🐛 Keep page-less changes from adding a nil page

Applying a commit locally rebuilds the object indices of every page its
changes name. Changes that touch no page, such as :mod-component, name
none, and their nil page id was rebuilt too: the file data in the store
gained a page under a nil key holding {:objects nil}. Every component
touch after an edit to a main added it, and undo never removed it.

Rebuild the indices only for the page ids the changes carry.

frontend/src/app/main/data/changes.cljs

@@ -75,7 +75,7 @@
        (not-empty)))
 
 (def ^:private xf:map-page-id
-  (map :page-id))
+  (keep :page-id))
 
 (def ^:private wasm-structural-change-types
   #{:add-obj :mov-objects})

frontend/test/frontend_tests/data/changes_test.cljs

@@ -0,0 +1,43 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) KALEIDOS SUBSIDIARY SL
+
+(ns frontend-tests.data.changes-test
+  (:require
+   [app.common.files.changes-builder :as pcb]
+   [app.common.test-helpers.composable.comp.setups :as setup]
+   [app.common.test-helpers.ids-map :as thi]
+   [app.main.data.changes :as dch]
+   [app.main.store :as st]
+   [app.plugins.reflow :as pwrf]
+   [cljs.test :as t :include-macros true]
+   [frontend-tests.composable-tests.interpreter :as ftm]))
+
+;; The component watcher schedules thumbnail renders that reach `window`,
+;; absent headless (see `ftm/install-thumbnail-noop!`).
+(t/use-fixtures :each
+  {:before (fn []
+             (thi/reset-idmap!)
+             (ftm/install-thumbnail-noop!))
+   :after  ftm/restore-thumbnail!})
+
+(t/deftest change-without-page-leaves-the-pages-alone
+  (t/async done
+    (ftm/install! (setup/simple-component-with-copy))
+    (let [file    (ftm/current-file)
+          pages   (set (keys (get-in file [:data :pages-index])))
+          changes (-> (pcb/empty-changes)
+                      (pcb/with-library-data (:data file))
+                      (pcb/update-component (thi/id :component1)
+                                            #(assoc % :annotation "Note")))]
+      (st/emit! (dch/commit-changes {:redo-changes (:redo-changes changes)
+                                     :undo-changes (:undo-changes changes)}))
+      (-> (pwrf/wait-for-layout-update nil 2000)
+          (.then (fn []
+                   (let [data (:data (ftm/current-file))]
+                     (t/is (= "Note" (get-in data [:components (thi/id :component1) :annotation])))
+                     (t/is (= pages (set (keys (:pages-index data))))))))
+          (.catch #(t/is false (str "the commit did not settle: " %)))
+          (.finally done)))))

frontend/test/frontend_tests/runner.cljs

@@ -10,6 +10,7 @@
    [frontend-tests.composable-tests.comp.sync-test]
    [frontend-tests.composable-tests.completion-contract-test]
    [frontend-tests.copy-as-svg-test]
+   [frontend-tests.data.changes-test]
    [frontend-tests.data.comments-filters-test]
    [frontend-tests.data.dashboard-test]
    [frontend-tests.data.event-test]
@@ -171,6 +172,7 @@
    'frontend-tests.composable-tests.comp.sync-test
    'frontend-tests.composable-tests.completion-contract-test
    'frontend-tests.copy-as-svg-test
+   'frontend-tests.data.changes-test
    'frontend-tests.data.comments-filters-test
    'frontend-tests.data.dashboard-test
    'frontend-tests.data.event-test