class PCSWMMError(RuntimeError):
    """Base exception for the SDK."""


class ProjectNotOpenError(PCSWMMError):
    """Raised when a PCSWMM project is required but is not open."""


class LayerNotFoundError(PCSWMMError):
    """Raised when a requested PCSWMM map layer is unavailable."""


class ResultsNotAvailableError(PCSWMMError):
    """Raised when simulation output or graph files are unavailable."""