The operation length of list cannot accept the arguments: , [""]

I got this error when I open my app. This block is in screen1.initialize block

I understand that "get start value" list is empty when beginning but I don't understand why is this cause an error? I put "logic and" block to check if its empty or not.
Thanks in advance.

Solution: length of list function does not accept empty start value so I put this block inside another if block as in photo:

(deleted unnecessary things in photo for not to confuse you.)

Would be great if you can show the blocks where you are calling new screen with start value.

OR you can share the Do It result for the get start value block, smthing this way


Tried to reproduce, could be the reason behind the error



If it is then, you need to correct the screen calling with perfect argument(s)

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of course, if it helps to you here is an example photo where first argument (1) represents no failure for my app, second and third ones are variables.

I need to work with assumptions and possible input, what I suggest to Do It over make a list block, what list, it is trying to make, whihc is to be forworded to next screen.


Live Development, Testing and Debugging

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here is do it result of make a list block. Already solved the problem but thank you for your help :slight_smile:

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What was the solution, please share with us, to help others to know and solve the similar issue. Thanks

I shared it with editing my first message and add it to "Solution" part

Another way it would be to check if list / start value is empty



Thanks, this seems more logical. I totally forgot "is list empty" block.

And one more level can be added to check weather it is a list ot not,


Else this could also result into


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