While selecting package versions:
error: Potentially incompatible change required to top-level dependency: themeteorchef:bert 2.1.1, was 2.2.0.
Constraints on package "themeteorchef:bert":
To allow potentially incompatible changes to top-level dependencies, you must pass --allow-incompatible-update on the command line.
Removing the package and re-adding it fixed it up right away.
On running the app today:
Removing the package and re-adding it fixed it up right away.