False error message when using a variable in timer expression

Attached you will find a reproducer. I have variable testInterval that is defined as a process variable. And also I have a timer event with expression #

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Each time I make any operation with a process intance I get error message "Could not find variable scope for variable testInterval".

At inital state this variable is not initialized and I get error message even if value of this variable is not required at the moment. I think it's better to generate this error if timer node is initialized and no variable is provided.

Could you please check that.