It is not really a bug in App Connect but how the number input works.
If you test the following code you get the exact same error.
<input type="number" id="nr">
<button onclick="document.getElementById('nr').value = '1.'">Set Value</button
When setting the value on a number input it will try to parse the string as a number and 1. throws an error here. This is an implementation of the browser and not something we can change.
Instead of using a number input use a standard text input.