JavaScript error when contributing to guild task

What you were expecting to happen, and what actually happened?

Contributing 7000 gold to complete guild task. Error message displayed - see screenshot
What are the steps to make it happen again?
Only happened once so far.
I had just tried to contribute to the task when I received a message stating someone had just contributed to the same task. Game crashed without an error message. When I restarted signs tried to contribute again,I received the following error.

Platform: android, Samsung s6

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