I'm not sure. It looks like a Mendix bug to me.
I suggest using the latest MTS version of Mendix Studio Pro. You could also file a ticket at https://support.mendix.com
In more detail: it tries to parse a string to a Long value, but the string is "1 “, so containing a whitespace in the end causing the error. Maybe you can relate it to something you entered.
I hope this helps.