app.py

"""Repro: downstream workflow nodes still run after an upstream node fails.

Two bound functions are chained: `first` -> `second`. `first` always raises,
so `second` should never run. Instead, `second` executes with `None` as its
input: the canvas shows "got: None" on the node, and the server log prints
"second() called with None".
"""

import gradio as gr


def first(x: str) -> str:
    raise ValueError("boom")


def second(x: str) -> str:
    print(f"second() called with {x!r}")
    return f"got: {x}"


wf = gr.Workflow(
    graph="workflow.json",
    bind={"first": first, "second": second},
    edges=[("first", "second")],
)

if __name__ == "__main__":
    wf.launch()