fix: dont throw error when Xvfb is already running (which is fine)

Author: pimlie

src/utils/commands/xvfb.js

@@ -77,6 +77,11 @@ export default class Xvfb {
 
       if (code === 1) {
         const error = stderr.match(/\(EE\) (?!\(EE\))(.+?)$/m)[1] || stderr
+        if (stderr.includes('already active for display')) {
+          console.warn(error) // eslint-disable-line no-console
+          return
+        }
+
         throw new BrowserError(`Failed to start Xvfb${error ? ', ' : ''}${error}`)
       }
     })