fix: Various React errors in console

app/components/Sidebar/Main.js

@@ -45,11 +45,13 @@ class MainSidebar extends React.Component<Props> {
     this.props.documents.fetchDrafts();
   }
 
-  handleCreateCollection = () => {
+  handleCreateCollection = (ev: SyntheticEvent<>) => {
+    ev.preventDefault();
     this.props.ui.setActiveModal('collection-new');
   };
 
-  handleInviteModalOpen = () => {
+  handleInviteModalOpen = (ev: SyntheticEvent<>) => {
+    ev.preventDefault();
     this.inviteModalOpen = true;
   };
 
@@ -145,6 +147,7 @@ class MainSidebar extends React.Component<Props> {
               />
               {can.invite && (
                 <SidebarLink
+                  to="/settings/people"
                   onClick={this.handleInviteModalOpen}
                   icon={<PlusIcon />}
                   label="Invite people…"

app/components/Sidebar/components/Collections.js

@@ -66,9 +66,11 @@ class Collections extends React.Component<Props> {
           />
         ))}
         <SidebarLink
+          to="/collections"
           onClick={this.props.onCreateCollection}
           icon={<PlusIcon />}
           label="New collection…"
+          exact
         />
       </Flex>
     );

app/scenes/Document/components/Contents.js

@@ -51,6 +51,7 @@ export default function Contents({ document }: Props) {
           <List>
             {headings.map(heading => (
               <ListItem
+                key={heading.slug}
                 level={heading.level}
                 active={activeSlug === heading.slug}
               >