Cantera version

2.5.0a3 (with YAML PR merged)

Operating System

Any

Python/MATLAB version

Any

With the new YAML input files, we are converting CK input files to YAML with the ck2yaml.py script during the build process. This script requires NumPy and ruamel_yaml (or ruamel.yaml), even if the Python interface is not being built. These packages should be checked for during the build process and a useful error message should be shown to the user. The current behavior is a ModuleNotFoundError on the first attempted conversion.