Merge pull request #14 from Rubinhuang9239/fix/prevent-duplicate-decl…

…arations

fix: prevent duplicate-declarations by check if WC is already exist.

src/index.ts

@@ -3,4 +3,4 @@ import { WaterfallElement } from './waterfall'
 export * from './waterfall'
 export type { WaterfallProps } from './layout'
 
-customElements.define('wc-waterfall', WaterfallElement)
+if (!customElements.get('wc-waterfall')) { customElements.define('wc-waterfall', WaterfallElement); }