Fix webContents event leak

Author: ECRomaneli

.vscode/launch.json

@@ -6,7 +6,7 @@
             "type": "node",
             "request": "launch",
             "runtimeExecutable": "${workspaceFolder}/node_modules/.bin/electron",
-            "args": ["${workspaceFolder}/test/sample.js"],
+            "args": ["--trace-warnings", "${workspaceFolder}/test/sample.js"],
             "preLaunchTask": "build:dev",
             "env": {
                 "NODE_ENV": "development"

package.json

@@ -22,7 +22,7 @@
     "build": "npm run clean && webpack",
     "build:dev": "npm run clean && NODE_ENV=development webpack",
     "dev": "webpack --mode development --watch",
-    "sample": "electron test/sample.js"
+    "sample": "electron --trace-warnings test/sample.js"
   },
   "repository": {
     "type": "git",

src/main.ts

@@ -68,8 +68,10 @@ class Findbar {
     if (!this.findableContents) { throw new Error('There are no searchable web contents.');  }
 
     this.findableContents._findbar = this;
-
-    this.findableContents.once('destroyed', () => { this.detach(); });
+    this.findableContents.prependOnceListener('destroyed', () => { this.detach(); });
+    this.findableContents.prependListener('found-in-page', (_e, result: FindInPageResult) => {
+      this.sendMatchesCount(result.activeMatchOrdinal, result.matches);
+    });
     this.updateParentWindow(parent);
   }
 
@@ -369,12 +371,6 @@ class Findbar {
     this.window!.webContents.prependListener('before-input-event', (event, input) => {
       this.registerKeyboardShortcuts(event, input);
     });
-    this.findableContents.prependOnceListener('destroyed', () => {
-      this.close();
-    });
-    this.findableContents.prependListener('found-in-page', (_e, result: FindInPageResult) => {
-      this.sendMatchesCount(result.activeMatchOrdinal, result.matches);
-    });
   }
 
   private sendMatchesCount(active: number, total: number): void {