Allow empty string "" in columns to be overridden with default values in priors

[PaulJonasJost]

The check only looked for whether it was not a string, but empty string values that are passed as "" were not caught here. This should fix the error.

[dilpath]

Fine as is

[dilpath]

IMO the default can come first, and the override can then be stated in the "positive" case, instead of nots. This is how it's mostly done elsewhere in the code as I recall.

But fine as is too.

This suggestion is for the changed code too, but github wouldn't let me edit the block.

Suggested change

	dist_type = d.get(f"{type_}PriorType", C.PARAMETER_SCALE_UNIFORM)
	dist_type = C.PARAMETER_SCALE_UNIFORM
	if _table_dist_type := d.get(f"{type_}PriorType") and (isinstance(_table_dist_type, str) or not np.isnan(_table_dist_type)):
	dist_type = _table_dist_type

[dweindl]

Thanks.