pub fn validate(app: &str) -> Result<(), String>Expand description
Parses and validates an app’s fragment source between the prelude and
the epilogue. Err carries naga’s message with line numbers moved into
the app’s own numbering, so a caller can print it as-is.
This is 55-73 us for a typical source, which is why add_fragment is
idempotent: a view that registers every frame should pay a comparison,
not this.