dropdown throws "event is not defined" error in PrimeNG v8.0.2 on Firefox

[thaihacong]

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Plunkr Case (Bug Reports)
https://stackblitz.com/edit/github-tlabav?file=package.json
or,
https://www.primefaces.org/primeng/#/dropdown

Current behavior
Click on the dropdown, then click outside.
Firefox throws error ReferenceError: event is not defined in console
The error does not happen on Chrome.

Expected behavior
There should be no console errors on all browsers.

• Angular version: 8.1.3

• PrimeNG version: 8.0.2
  The error does not happen on PrimeNG v8.0.1.
  It could be because of this commit 2944fce

• Browser: Firefox 40.0.3 on MacOS, Firefox 60.6.1esr (64-bit) on CentOS Linux release 7.6.1810

[benoitbb]

Same problem here

[yigitfindikli]

Hi @thaihacong ,
I couldn't replicate it with Firefox 67.0.4. What is your Firefox version?

[thaihacong]

@yigitfindikli Thank you for your fast response.
I could also not reproduce it on

• Firefox 68.0.1 (64-Bit) on Windows 10
• Firefox 68.0.1 (64-Bit) on MacOS

But the error happens on

• Firefox 40.0.3 on MacOS
• Firefox 60.6.1esr (64-bit) on CentOS Linux release 7.6.1810