SourceMod's build scripts has 3 ways of locating dependencies:
- Use the value of the associated cli option, for the option for hl2 sdks, it's the folder containing the sdk folders.
- Use the value obtained from the associated environment variable (skipped if option value is provided).
- Traverse the folder hierarchy from the current working directory until a valid folder is located.
SourceMod couldn't locate the folder for Day of Infamy.
Should all 3 ways fail, the script will raise a Python exception.