A host word signals failure by throwing across the JS boundary, and the
browser runtime reported that exception with its Debug form, so an
empty-stack RESIZE surfaced as
call_func(134) failed: JsValue(Error: Stack underflow ...)
with the engine's JS stack trace glued on. The thrown message IS the
Forth message, so take it verbatim: 'Stack underflow', the same text the
native CLI prints. Exceptions without a message keep the call context --
those are genuine runtime faults, not Forth throws.
CATCH is unaffected: it reads the throw code from its own channel rather
than parsing messages. Verified against a fresh VM in Node (initSync +
WaferRepl): host-word underflow, compiled-guard underflow, THROW,
unknown word and ' RESIZE CATCH . all match the native CLI.
Ships as v0.2.4.
Oleksandr Kozachuk
4769987b20