lib: Drop unnecessary optional chaining

DialogFooter already accesses other fields of `action`, and thus it
can't be undefined.

apply_modal_dialog() already assumes that `event` is defined, as it
calls `.preventDefault()` on it (which would crashs if undefined).

Spotted by Coverity.

Author: martinpitt

pkg/lib/cockpit-components-dialog.jsx

@@ -169,7 +169,7 @@ class DialogFooter extends React.Component {
                 variant={ variant }
                 isDanger={ action.danger }
                 onClick={ this.action_click.bind(this, action.clicked) }
-                isDisabled={ actions_disabled || action?.disabled }
+                isDisabled={ actions_disabled || action.disabled }
             >{ caption }</Button>
             );
         });
@@ -344,7 +344,7 @@ export function show_modal_dialog(props, footerProps) {
 }
 
 export function apply_modal_dialog(event) {
-    const dialog = event?.target?.closest("[role=dialog]");
+    const dialog = event.target?.closest("[role=dialog]");
     const button = dialog?.querySelector("button.apply");
 
     if (button) {