Handling errors
Unlike REST, which makes use of the HTTP status codes, gRPC uses a Status model that contains its error codes and optional error message (string).
If you remember, you have used the special class called Error for containing the error details because HTTP error codes contain limited information. Similarly, the gRPC error Status model is limited to code and an optional message (string). You can't have sufficient error details that the client can use to handle the error or retry. You can make use of the richer error model as described at https://cloud.google.com/apis/design/errors#error_model, which allows you to pass detailed error information back to the client. You can also find the error models in the next code block for quick reference:
package google.rpc;
message Status {
// actual error code is defined by `google.rpc.Code`.
int32 code = 1;
// A developer-facing human-readable error message
string message...