Checklist

• I have searched the existing issues for similar issues.
• I added a very descriptive title to this issue.
• I have provided sufficient information below to help reproduce this issue.

Summary

I'm trying to use buttons to trigger steps in my app, using on_click callbacks.

Errors sometimes occur within the callbacks, which I would like to handle in a unified way on the frontend (e.g. displaying the error as well as some debug information, like the current st.sessionstate).

However, I can't figure out how to catch errors that are triggered in callbacks, which seem to be executed outside the normal flow of the app.

I could put error handling inside each callback, or write a decorator, but it would be much more convenient and intuitive if I could put the widget in a try:... except:... block and handle errors that way.

Reproducible Code Example

import streamlit as st

def raise_error():
    raise RuntimeError("This is an error")

try:
    if st.button("Expected behavior"):
        raise_error()
except Exception as e:
    st.text("This works, and the error can be handled here")

try:
    st.button("Undesired behavior", on_click=raise_error)
except Exception as e:
    st.text("This block is never executed, and the callback instead triggers Streamlit's default error handler")

Steps To Reproduce

1. An error is raised in a callback (e.g. a function passed to a button's on_click)
2. The widget that holds the callback is wrapped in a try:... except:... block
3. Trigger the widget's callback (e.g. by clicking the button)
4. The try:... except:... block is not executed, and instead the error in the callback is handled by Streamlit's default error handler

Expected Behavior

The error is caught by the except:... block and can be handled there.

Current Behavior

The callback is executed outside of the flow of the user written code and triggers the default error handling, ignoring the try:... except:...

Is this a regression?

• Yes, this used to work in a previous version.

Debug info

• Streamlit version: 1.23.1
• Python version: 3.10.2
• Operating System: OSX
• Browser: Chrome
• Virtual environment: pyenv

Additional Information

No response

Are you willing to submit a PR?

• Yes, I am willing to submit a PR!