fix(nightModeEpic): Colocate in app

This moves epic into main app and prevents it running server side

client/epics/night-mode-epic.js

@@ -1,59 +0,0 @@
-import _ from 'lodash';
-import { Observable } from 'rx';
-import { ofType } from 'redux-epic';
-import store from 'store';
-
-import { themes } from '../../common/utils/themes.js';
-import { postJSON$ } from '../../common/utils/ajax-stream.js';
-import {
-  types,
-
-  postThemeComplete,
-  createErrorObservable,
-
-  themeSelector,
-  usernameSelector,
-  csrfSelector
-} from '../../common/app/redux';
-
-function persistTheme(theme) {
-  store.set('fcc-theme', theme);
-}
-
-export default function nightModeSaga(
-  actions,
-  { getState },
-  { document: { body } }
-) {
-  const toggleBodyClass = actions
-    ::ofType(
-      types.fetchUser.complete,
-      types.toggleNightMode,
-      types.postThemeComplete
-    )
-    .map(_.flow(getState, themeSelector))
-    // catch existing night mode users
-    .do(persistTheme)
-    .do(theme => {
-      if (theme === themes.night) {
-        body.classList.add(themes.night);
-      } else {
-        body.classList.remove(themes.night);
-      }
-    })
-    .ignoreElements();
-
-  const postThemeEpic = actions::ofType(types.toggleNightMode)
-    .debounce(250)
-    .flatMapLatest(() => {
-      const _csrf = csrfSelector(getState());
-      const theme = themeSelector(getState());
-      const username = usernameSelector(getState());
-      return postJSON$('/update-my-theme', { _csrf, theme })
-        .pluck('updatedTo')
-        .map(theme => postThemeComplete(username, theme))
-        .catch(createErrorObservable);
-    });
-
-  return Observable.merge(toggleBodyClass, postThemeEpic);
-}

common/app/redux/night-mode-epic.js

@@ -0,0 +1,64 @@
+import _ from 'lodash';
+import { Observable } from 'rx';
+import { ofType } from 'redux-epic';
+import store from 'store';
+
+import { themes } from '../../utils/themes.js';
+import { postJSON$ } from '../../utils/ajax-stream.js';
+import {
+  types,
+
+  postThemeComplete,
+  createErrorObservable,
+
+  themeSelector,
+  usernameSelector,
+  csrfSelector
+} from './index.js';
+
+function persistTheme(theme) {
+  store.set('fcc-theme', theme);
+}
+
+export default function nightModeEpic(
+  actions,
+  { getState },
+  { document }
+) {
+  return Observable.of(document)
+    // if document is undefined we do nothing (ssr trap)
+    .filter(Boolean)
+    .flatMap(({ body }) => {
+      const toggleBodyClass = actions
+        ::ofType(
+          types.fetchUser.complete,
+          types.toggleNightMode,
+          types.postThemeComplete
+        )
+        .map(_.flow(getState, themeSelector))
+        // catch existing night mode users
+        .do(persistTheme)
+        .do(theme => {
+          if (theme === themes.night) {
+            body.classList.add(themes.night);
+          } else {
+            body.classList.remove(themes.night);
+          }
+        })
+        .ignoreElements();
+
+      const postThemeEpic = actions::ofType(types.toggleNightMode)
+        .debounce(250)
+        .flatMapLatest(() => {
+          const _csrf = csrfSelector(getState());
+          const theme = themeSelector(getState());
+          const username = usernameSelector(getState());
+          return postJSON$('/update-my-theme', { _csrf, theme })
+            .pluck('updatedTo')
+            .map(theme => postThemeComplete(username, theme))
+            .catch(createErrorObservable);
+        });
+
+      return Observable.merge(toggleBodyClass, postThemeEpic);
+    });
+}