Returns true after this UnityWebRequest encounters a system error. (Read Only)
Examples of system errors include failure to resolve a DNS entry, a socket error or a redirect limit being exceeded. When this property returns true, the error property will contain a human-readable string describing the error.
Note: Error-type server return codes, such as 404/Not Found and 500/Internal Server Error, are reflected in the isHttpError property, not the isNetworkError property.
Additional resources: responseCode, isHttpError.