Currently, a NullReferenceException is thrown because of the incorrect structure.
As a workaround, the exception can be handled using the Handling Exceptions mechanism.
Update:
When importing documents with invalid structure of path construction operators an InvalidGraphicOperandsCountException is thrown which could be handled using the Handling Exceptions mechanism.
PdfFormatProvider provider = new PdfFormatProvider();
provider.ImportSettings.DocumentUnhandledException += this.ImportSettings_DocumentUnhandledException;
private void ImportSettings_DocumentUnhandledException(object sender, DocumentUnhandledExceptionEventArgs e)
{
if (e.Exception is InvalidGraphicOperandsCountException)
{
e.Handled = true;
}
}