[Backport staging] Fix create subspace dialog not working (#10656)

Co-authored-by: Michael Telatynski <[email protected]>

Author: RiotRobot

src/components/views/dialogs/CreateSubspaceDialog.tsx

@@ -56,18 +56,22 @@ const CreateSubspaceDialog: React.FC<IProps> = ({ space, onAddExistingSpaceClick
 
     const onCreateSubspaceClick = async (e: ButtonEvent): Promise<void> => {
         e.preventDefault();
-        if (busy || !spaceNameField.current || !spaceAliasField.current) return;
+        if (busy) return;
 
         setBusy(true);
         // require & validate the space name field
-        if (!(await spaceNameField.current.validate({ allowEmpty: false }))) {
+        if (spaceNameField.current && !(await spaceNameField.current.validate({ allowEmpty: false }))) {
             spaceNameField.current.focus();
             spaceNameField.current.validate({ allowEmpty: false, focused: true });
             setBusy(false);
             return;
         }
         // validate the space name alias field but do not require it
-        if (joinRule === JoinRule.Public && !(await spaceAliasField.current.validate({ allowEmpty: true }))) {
+        if (
+            spaceAliasField.current &&
+            joinRule === JoinRule.Public &&
+            (await spaceAliasField.current.validate({ allowEmpty: true }))
+        ) {
             spaceAliasField.current.focus();
             spaceAliasField.current.validate({ allowEmpty: true, focused: true });
             setBusy(false);