Answer architecture round 2: a first reach checks only a table's parent, loadReached splits into a batch that loads, runs and puts back, the manifest decodes strictly and reports every mistake, and ErrLoad marks a load failing in New too

CHANGELOG.md

@@ -126,7 +126,7 @@ replacement, and each removed path, column or flag.
   `sv_SE.sex[f].first-name[Kim]`, and a category with no columns names the record
   that gives it one.
 - A data source whose root holds a `.fejkdata.json` manifest with an `index` loads each
-  category on the first call reaching it, as the shipped set does, and a category failing
-  there returns an error wrapping `ErrLoad`, on which the CLI exits 1. A source without
+  category on the first call reaching it, as the shipped set does. Data failing to load,
+  in `New` or there, gives an error matching `ErrLoad`, and the CLI exits 1. A source without
   one loads in `New`, with the shipped categories it reads and every shipped category
   depending on one it replaces; the rest of the shipped set still loads on first reach.