fix: throw error when installilng duplicate pluign (#111)

Author: 0xtsukino

src/entries/Background/rpc.ts

@@ -921,6 +921,11 @@ async function handleInstallPluginRequest(request: BackgroundAction) {
         try {
           const hex = Buffer.from(arrayBuffer).toString('hex');
           const hash = await addPlugin(hex);
+
+          if (!hash) {
+            throw new Error('Plugin already exist.');
+          }
+
           await addPluginConfig(hash!, config);
           await addPluginMetadata(hash!, {
             ...metadata,

src/pages/Home/index.tsx

@@ -20,8 +20,6 @@ import {
   usePluginConfig,
   usePluginHashes,
 } from '../../reducers/plugins';
-import { PluginConfig } from '../../utils/misc';
-import { getPluginConfigByHash } from '../../entries/Background/db';
 import { fetchPluginHashes } from '../../utils/rpc';
 import DefaultPluginIcon from '../../assets/img/default-plugin-icon.png';
 
@@ -212,6 +210,8 @@ function PluginIcon({ hash }: { hash: string }) {
     onPluginClick();
   }, [onPluginClick, config]);
 
+  if (!config) return null;
+
   return (
     <button
       className={classNames(