Display notice instead of hide when Slack integration unavailable

app/routes/settings.js

@@ -30,9 +30,7 @@ export default function SettingsRoutes() {
       <Route exact path="/settings/shares" component={Shares} />
       <Route exact path="/settings/tokens" component={Tokens} />
       <Route exact path="/settings/notifications" component={Notifications} />
-      {env.SLACK_KEY && (
       <Route exact path="/settings/integrations/slack" component={Slack} />
-      )}
       {isHosted && (
         <Route exact path="/settings/integrations/zapier" component={Zapier} />
       )}

app/scenes/Settings/Slack.js

@@ -39,6 +39,7 @@ function Slack() {
   return (
     <Scene title="Slack" icon={<SlackIcon color="currentColor" />}>
       <Heading>Slack</Heading>
+
       {error === "access_denied" && (
         <Notice>
           <Trans>
@@ -62,9 +63,13 @@ function Slack() {
           components={{ em: <Code /> }}
         />
       </HelpText>
+      {env.SLACK_KEY ? (
+        <>
           <p>
             {commandIntegration ? (
-          <Button onClick={commandIntegration.delete}>{t("Disconnect")}</Button>
+              <Button onClick={commandIntegration.delete}>
+                {t("Disconnect")}
+              </Button>
             ) : (
               <SlackButton
                 scopes={["commands", "links:read", "links:write"]}
@@ -79,7 +84,8 @@ function Slack() {
           <HelpText>
             <Trans>
               Connect Outline collections to Slack channels and messages will be
-          automatically posted to Slack when documents are published or updated.
+              automatically posted to Slack when documents are published or
+              updated.
             </Trans>
           </HelpText>
 
@@ -128,6 +134,16 @@ function Slack() {
               );
             })}
           </List>
+        </>
+      ) : (
+        <Notice>
+          <Trans>
+            The Slack integration is currently disabled. Please set the
+            associated environment variables and restart the server to enable
+            the integration.
+          </Trans>
+        </Notice>
+      )}
     </Scene>
   );
 }