fix type error if If component

hyperglass/ui/components/util/if.tsx

@@ -1,6 +1,6 @@
 import type { TIf } from './types';
 
-export const If = (props: React.PropsWithChildren<TIf>): React.ReactNode | null => {
+export const If: React.FC<TIf> = (props: TIf) => {
   const { c, children } = props;
-  return c ? children : null;
+  return c ? <>{children}</> : null;
 };

hyperglass/ui/components/util/types.ts

@@ -1,3 +1,4 @@
 export interface TIf {
   c: boolean;
+  children?: React.ReactNode;
 }