Config conversion should not silently drop invalid docs

[Deeven-Seru]

Title:
Config conversion should fail on invalid v1 docs (no silent drop)

Prerequisites

• I searched the current open issues.

What are you trying to do that currently feels hard or impossible?

Trust that config conversion errors are surfaced instead of silently dropping sections.

Clear end goal (specific use‑case)

When a v1‑style config doc is malformed, I want a hard error that tells
me exactly which document is invalid, so I don’t end up with missing tools/sources at runtime.

Suggested Solution(s)

• In ConvertConfig, if a v1 doc can’t be coerced into the expected map shape, return an error.
• Include doc index + key path in the error.
• Provide a hint: if you intended v2 format, each doc needs kind + name.

Alternatives Considered

None — the current behavior is silent and makes debugging too slow.

Additional Details

Code pointer: cmd/internal/config.go → ConvertConfig.