What a follow may fail with: the follow request, the rail reload's
session-fatal failures (settled re-raises only those), and the action's own
refusals (the screen on top, the transition). The item definitions' enter
errors are part of it through itemHandlesOf's type; this list is checked
against that effect where the action is declared. The rail's data check is
not here: the reload's rows are decoded by suggestedRowsOf before they
become item handles, so a drift is the background failure the visit reports,
not an error of the action.
What a follow may fail with: the follow request, the rail reload's session-fatal failures (
settledre-raises only those), and the action's own refusals (the screen on top, the transition). The item definitions' enter errors are part of it throughitemHandlesOf's type; this list is checked against that effect where the action is declared. The rail's data check is not here: the reload's rows are decoded bysuggestedRowsOfbefore they become item handles, so a drift is the background failure the visit reports, not an error of the action.