fix: log plugin load failures to stderr

[YoannDev90]

Issue for this PR

Closes #41817

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Plugin load errors are only published as a Session.Event.Error in publishPluginError (packages/opencode/src/plugin/index.ts). The desktop renderer does not consume that event, so a plugin that fails to load in the desktop app is invisible: the entry appears in the plugin list, nothing is logged, and no tools register. Example: plugins importing bun:sqlite on the Node plugin host (see #41817).

Change: publishPluginError also writes the message to stderr, which the desktop sidecar pipes into the server log, so failures are diagnosable.

The bun:sqlite shim itself is tracked separately in #41817.

How did you verify your code works?

Could not run the desktop build locally (no Node/pnpm toolchain in the environment). The change is a one-line addition to the existing error path, using the Node process.stderr API; the existing event publish is untouched.

Screenshots / recordings

N/A (no UI change).

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

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[github-actions]

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[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potentially Related PR Found:

• PR fix(tui): publish session event when custom tool import fails #37411: fix(tui): publish session event when custom tool import fails - This is related in that it addresses error visibility for tool/plugin failures, though it's TUI-specific. However, it shows a pattern of handling import failures via Session.Event.Error, which is exactly what the current PR is addressing more broadly.

However, PR #37411 is about publishing the event (which PR #41818 already does), not about logging to stderr for visibility in desktop logs. The current PR (41818) is a different approach focused on stderr logging.

Conclusion:

No true duplicate PRs found. PR #37411 is related but addresses a different aspect (TUI event publishing vs. desktop stderr logging).

[YoannDev90]

Hmm will fix the PR tomorrow

[github-actions]

This pull request has been automatically closed because it was not updated to meet our contributing guidelines within the 2-hour window.

Feel free to open a new pull request that follows our guidelines.

[YoannDev90]

2 hour ...