ConcurrentModificationException onUpdatePressed(LibraryManagerUI)

[imrehorvath]

Hi! I'd like to report an issue (bug) with the Arduino IDE.
macOS 10.15.5
Arduino IDE 1.8.13 (Official build)

The issue can be reproduced with the following scenario.
On a freshly started Arduino IDE, I check for updatable packages, by opening Tools > Board: "..." > Boards Manager...
I wait to load, then I select Type Updatable. After this I click Close.
Then I open the Library Manager by clicking Sketch > Include Library > Manage Libraries...
While it loads, the below exception is thrown.

java.util.ConcurrentModificationException
java.lang.RuntimeException: java.util.ConcurrentModificationException
	at cc.arduino.contributions.libraries.ui.LibraryManagerUI.lambda$onUpdatePressed$2(LibraryManagerUI.java:207)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.util.ConcurrentModificationException
	at java.util.ArrayList.sort(ArrayList.java:1464)
	at java.util.Collections.sort(Collections.java:177)
	at cc.arduino.contributions.libraries.ui.LibrariesIndexTableModel.updateContributions(LibrariesIndexTableModel.java:208)
	at cc.arduino.contributions.libraries.ui.LibrariesIndexTableModel.update(LibrariesIndexTableModel.java:138)
	at cc.arduino.contributions.libraries.ui.LibraryManagerUI.lambda$onUpdatePressed$2(LibraryManagerUI.java:204)
	... 1 more