did archlens just crash on this?

[mircealungu]

in this PR:

zeeguu/api#470

Then PR was opened, AR rendered this dependency graph:

Then, I removed some dependencies, the action ran again, and the image got updated to this:

Then I removed the last broken dependency... the action ran again, and now there's no more image!
Did the action crash? Or why don't I see anything anymore in here?

[mircealungu]

Investigation Findings

I investigated the workflow logs and found the root cause:

What Happened

1. Run 319 started after the last dependency was removed
2. The 319-old/ folder was created successfully (capturing the "before" state)
3. Diff image generation failed with a PlantUML error
4. The PR comment was posted but with an empty view list

Error from Workflow Logs

From workflow run 21440306420:

raise PlantUMLHTTPError(response, content)
AttributeError: 'PlantUMLHTTPError' object has no attribute 'message'

Evidence

Looking at the _archlens_diff branch:

• diagrams-470/318-zeeguu-api-diff-top-level-view-depth-1.png exists (shows 1 dependency)
• diagrams-470/319-old/ exists (before state was captured)
• No 319-*.png diff images were generated (PlantUML crashed)

Root Cause

ArchLens/PlantUML crashes when trying to render a diff where an edge is completely removed (count goes from 1 → 0). The diagram generation fails, resulting in an empty PR comment.

Suggested Fix

The diff rendering logic needs to handle the case where an edge is entirely removed, not just reduced in count.

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Note: I also created archlens/Render-Diff-on-PR#4 before realizing this issue existed - that can be closed as duplicate.