Normally the type of a node's output attribute will change based on the operation.
For example, the attribute color ramp node will always upgrade the type of the output to "Color".
However, the type of built-in attributes cannot change, so the writing fails.
There are two options to solve this:
- Change every node that writes an attribute to support writing with all types
- Use implicit conversion when writing to a built-in attribute
The second option should be implemented for this task, which will likely involve changing OutputAttributePtr.
The first option can be implemented for some nodes later if the implicit conversion ends up being a performance bottleneck.
