Add None check before writing to stderr
Add None check before writing to stderr

AzureAD/microsoft-authentication-library-for-objc,AzureAD/microsoft-authentication-library-for-objc,AzureAD/microsoft-authentication-library-for-objc,AzureAD/microsoft-authentication-library-for-objc,AzureAD/microsoft-authentication-library-for-objc