Why I get the error: "Attempted to unrender a fragment that was not rendered" when migrating from ractive.js 0.3.9 to 0.5.5 - migration

Question

I have a long, complex and a little dirty set of templates that works OK in 0.3.9 but not in 0.5.5 where I get the error: "Attempted to unrender a fragment that was not rendered".
My template is very complex but I could reproduce a slice that works in 0.3.9 but not in 0.5.5.
This is how it works OK in 0.3.9: http://jsfiddle.net/Katio/ujx2e/
This template in 0.5.5 shows the mentioned error: http://jsfiddle.net/Katio/W3Lus/
Attempted to unrender a fragment that was not rendered
Edit 1:
Thaylon has opened an issue in Ractive project on Github:
https://github.com/ractivejs/ractive/issues/1003

Answer 1

I must admit I'm not sure what the root of the problem is.
Yet, change the beginning of line 33 in your template from:
{{^.responsable}}<span class="redOutline" data-validationmess="Solicitud ({{num+1}}) '{{../../nombreSubdata.values[0]}}', sección '{{nombre.values[0]}}', responsable no asignado.">(responsable no asignado)</span>{{/.responsable}}
to:
{{^responsable}}<span class="redOutline" data-validationmess="Solicitud ({{num+1}}) '{{../../nombreSubdata.values[0]}}', sección '{{nombre.values[0]}}', responsable no asignado.">(responsable no asignado)</span>{{/responsable}}
and it will render.
http://jsfiddle.net/W3Lus/2/
Edit
A pretty minimal example that exhibits the error is: http://jsfiddle.net/W3Lus/9/
Removing any part, even the static <option>, it will render.
Doesnt look like you're doing anything wrong, seems to be a bug.
Edit
I assume binding the select value to {{.responsable}}, when it does not resolve to anything, causes this, as long as there is any option in the select that actually would be bound to the non-existing value.
Edit
Minimal examples with different buggy results:
http://jsfiddle.net/W3Lus/13/
http://jsfiddle.net/W3Lus/12/
One wont render at all, the other wont render a part that it should.