This is achieved by letting the index sync thread wait until
reindex-chainstate is finished.
This also disables the pruning check when reindexing the chainstate (which is
incompatible with prune mode) because there would be no chain at this point
in init.
The src/node/ directory contains code that needs to access node state
(state in CChain, CBlockIndex, CCoinsView, CTxMemPool, and similar
classes).
Code in src/node/ is meant to be segregated from code in
src/wallet/ and src/qt/, to ensure wallet and GUI
code changes don't interfere with node operation, to allow wallet and GUI code
to run in separate processes, and to perhaps eventually allow wallet and GUI
code to be maintained in separate source repositories.
As a rule of thumb, code in one of the src/node/,
src/wallet/, or src/qt/ directories should avoid
calling code in the other directories directly, and only invoke it indirectly
through the more limited src/interfaces/ classes.
This directory is at the moment
sparsely populated. Eventually more substantial files like
src/validation.cpp and
src/txmempool.cpp might be moved there.