Loading API Format prompt workflow should handle missing nodes and still load graph (align behavior with loading of normal workflows)

Prerequisites

• I am running the latest version of ComfyUI
• I have searched existing issues to make sure this isn't a duplicate
• I have tested with all custom nodes disabled (see how)

What happened?

Expected: Workflow should load even if specific custom node(s) are not installed, while displaying the appropriate dialogue about the missing custom node(s).

Actual: The workflow does not load at all, although the correct dialogue for the missing custom node(s) is shown.

Steps to Reproduce

1. Make sure not to have Comfy-Deploy (https://github.com/BennyKok/comfyui-deploy) and ComfyUI-Omini-Kontext (https://github.com/tercumantanumut/ComfyUI-Omini-Kontext) installed.
2. Attempt to drag and drop both/either of the workflows.
3. Notice the correct dialogue pop-up, but the workflow(s) not importing.

https://github.com/user-attachments/assets/3dde3364-11c0-439c-9f95-1fd3e1d2b451

kontext-single-workflow.json

kontext-multi-workflow.json

How is this affecting you?

Feature doesn't work as expected

ComfyUI Frontend Version

1.26.6

Browser

Chrome/Chromium

Console Errors

Logs

Additional Context

Workflows load correctly if the required custom node(s) are already installed before importing. However, if a workflow was previously loaded and the custom node(s) are uninstalled afterward, ComfyUI can still launch that workflow successfully on startup, since it reloads the last saved session.

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