fix(langgraph): Re-throw NodeInterrupt errors from ToolNode for HITL.

[jaredhanson]

This changes ToolNode to always re-throw NodeInterrupt errors, rather than feeding errors back into the agent.

As documented here, the intent of NodeInterrupt is to act as a breakpoint for when a human needs to be brought into the loop. This works as intended when thrown from a step function. However, when wrapped in a ToolNode, the default behavior traps NodeInterrupt and feeds it back to the agent. This is unexpected, since if a human is necessary the agent can't recover on its own.

Furthermore, setting handleToolErrors to false is a way to workaround this, but that then requires the developer to feed all other non-NodeInterrupt errors back manually (which is also unexpected).

The best default behavior seems to be feeding all errors except NodeInterrupt back, and re-throwing NodeInterrupt so the application can handle it appropriately.

I discussed this with @jacoblee93 on an internal Slack channel.

Twitter: @jaredhanson

[jacoblee93]

Thank you!