E402 - Invalid or duplicate asset filename

Cause

Either an asset filename resolves to . or .. (illegal), or two different asset paths in the deck resolve to the same basename — they would collide in the bundled asset namespace.

Example

// slide A
{ image: "../shared/diagram.png" }
// slide B
{ image: "./assets/diagram.png" }   // same basename: 'diagram.png'

How to fix

Rename one of the conflicting assets, or move both into a single shared assets directory so they reference the same file.