### What needs to get done Check if the build plan will create multiple artefacts on any particular architecture. If it will, then raise an error before sending the project to Launchpad. ### Why it needs to get done Launchpad cannot build multiple artefacts on the same architecture. It prepares a build environment and runs Snapcraft in destructive mode without specifying `--build-for` or `--platform`. Snapcraft will refuse to run if multiple builds aretfacts can be built. This is a poor UX because it occurs after the project is uploaded to Launchpad and requires the user to read the logfile downloaded from Launchpad. The following fails in Launchpad: ``` platforms: amd64: build-on: amd64 build-for: amd64 platform2: build-on: amd64 build-for: riscv64 ```