Vignette on estimate_infections() examples has errors in code chunks

[jamesmbaazam]

The example on passing a truncation distribution to estimate_infections() errors in the vignette here.

As an aside, should we generally ensure that the vignettes' model specifications do not produce divergences?

[sbfnk]

@jamesmbaazam are you doing this one? We should fix this as a priority because it breaks some functionality.

[jamesmbaazam]

Not currently but will compile this vignette in the tolerance branch now to see if it fixes it.

UPDATE:

• The vignette is still broken. Something to do with retrieving the "weight_prior" attribute from a composite distribution.

I'm currently reviewing #724 and trying to finish #695 so I've removed my self-assignment here.