[ctx_error_unknown_status] doc

interceptor.go

@@ -72,9 +72,12 @@ type UnaryServerInfo struct {
 }
 
 // UnaryHandler defines the handler invoked by UnaryServerInterceptor to complete the normal
-// execution of a unary RPC. If a UnaryHandler returns an error, it should be produced by the
-// status package, or else gRPC will use codes.Unknown as the status code and err.Error() as
-// the status message of the RPC.
+// execution of a unary RPC.
+//
+// If a UnaryHandler returns an error, it should either be produced by the
+// status package, or be one of the context errors. Otherwise, gRPC will use
+// codes.Unknown as the status code and err.Error() as the status message of the
+// RPC.
 type UnaryHandler func(ctx context.Context, req interface{}) (interface{}, error)
 
 // UnaryServerInterceptor provides a hook to intercept the execution of a unary RPC on the server. info

stream.go

@@ -46,10 +46,12 @@ import (
 )
 
 // StreamHandler defines the handler called by gRPC server to complete the
-// execution of a streaming RPC. If a StreamHandler returns an error, it
-// should be produced by the status package, or else gRPC will use
-// codes.Unknown as the status code and err.Error() as the status message
-// of the RPC.
+// execution of a streaming RPC.
+//
+// If a StreamHandler returns an error, it should either be produced by the
+// status package, or be one of the context errors. Otherwise, gRPC will use
+// codes.Unknown as the status code and err.Error() as the status message of the
+// RPC.
 type StreamHandler func(srv interface{}, stream ServerStream) error
 
 // StreamDesc represents a streaming RPC service's method specification.  Used