fix(browser-runner): reject promise on error

docs/api.md

@@ -882,6 +882,8 @@ a single instance of [BrowserContext].
 
 Closes Chromium and all of its pages (if any were opened). The [Browser] object itself is considered to be disposed and cannot be used anymore.
 
+During the process of closing the browser, Puppeteer attempts to delete the temp folder created exclusively for this browser instance. If this fails (either because a file in the temp folder is locked by another process or because of insufficient permissions) an error is logged. This implies that: a) the folder and/or its content is not fully deleted; and b) the connection with the browser is not properly disposed (see [browser.disconnect()](#browserdisconnect)).
+
 #### browser.createIncognitoBrowserContext()
 
 - returns: <[Promise]<[BrowserContext]>>

src/node/BrowserRunner.ts

@@ -91,14 +91,17 @@ export class BrowserRunner {
       this.proc.stdout.pipe(process.stdout);
     }
     this._closed = false;
-    this._processClosing = new Promise((fulfill) => {
+    this._processClosing = new Promise((fulfill, reject) => {
       this.proc.once('exit', () => {
         this._closed = true;
         // Cleanup as processes exit.
         if (this._tempDirectory) {
           removeFolderAsync(this._tempDirectory)
             .then(() => fulfill())
-            .catch((error) => console.error(error));
+            .catch((error) => {
+              console.error(error);
+              reject(error);
+            });
         } else {
           fulfill();
         }