Error: Generated byte code contains an operand stack underflow.

I discovered a situation which results in the error above. It had me scratching my head for quite some time until I found the problem:

I had some markup which can be distilled to the following:
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A Spectrum Card has a member called `quickActions` which is assigned a `QuickActions` component. It can also be assigned a `Footer` element. Specifying the element (`sp:CardFooter`) before the `quickActions` setter, caused the stack underflow.

The following modification fixes the error:
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I don't know if the order of the declarations is a hard requirement, but if it is, we need a better error message...