Error values and inspection.
The Error
type is the argument to throw
, parameter of catch
.
The Error
type is opaque.
Error value resulting from async
computations
Error code to classify different kinds of user and system errors:
type ErrorCode = {
// Fatal error.
#system_fatal;
// Transient error.
#system_transient;
// Destination invalid.
#destination_invalid;
// Explicit reject by canister code.
#canister_reject;
// Canister trapped.
#canister_error;
// Future error code (with unrecognized numeric code).
#future : Nat32;
// Error issuing inter-canister call
// (indicating destination queue full or freezing threshold crossed).
#call_error : { err_code : Nat32 }
};
public let reject : (message : Text) -> Error
Create an error from the message with the code #canister_reject
.
Example:
import Error "mo:base/Error";
Error.reject("Example error") // can be used as throw argument
public let code : (error : Error) -> ErrorCode
Returns the code of an error.
Example:
import Error "mo:base/Error";
let error = Error.reject("Example error");
Error.code(error) // #canister_reject
public let message : (error : Error) -> Text
Returns the message of an error.
Example:
import Error "mo:base/Error";
import Debug "mo:base/Debug";
let error = Error.reject("Example error");
Error.message(error) // "Example error"