Function component_issues 

pub fn component_issues(
    flat: &FlatComponent,
    options: &ReduceOptions,
    lookup: &dyn Fn(&str) -> Option<FlatComponent>,
) -> Vec<ReduceIssue>

VAPP-103 rfix: the issues ONE component raises on its own (an unknown component or basic mapping, its props, visible, children it may not take, slots it lacks): what a streamed updateComponents reports at once while the tree reduces lazily. Tree issues (missing ids, cycles, depth, limits) come with the next reduce. lookup = the surface’s components (a basic component consumes its children).