“Error: undefined” if a cf7 input value isn’t correct or missing

If an input-value of an cf7-field isn’t as except (ex. a wrong email address) the browser response with an error which says “Error:undefined” after submitting the form. If the customer clicks “OK” and would like to correct the input-value the message always shows up again. This is caused by this plugin, because the values of the rangeslider will be 0 instead of the predefined numbers. Is there any solution to fix this issue?

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