The result that was the wrong variant.
OptionalcauseReadonlyresultThe result that triggered the error.
OptionalstackStaticstackThe Error.stackTraceLimit property specifies the number of stack frames
collected by a stack trace (whether generated by new Error().stack or
Error.captureStackTrace(obj)).
The default value is 10 but may be set to any valid JavaScript number. Changes
will affect any stack trace captured after the value has been changed.
If set to a non-number value, or set to a negative number, stack traces will not capture any frames.
StaticcaptureCreates a .stack property on targetObject, which when accessed returns
a string representing the location in the code at which
Error.captureStackTrace() was called.
const myObject = {};
Error.captureStackTrace(myObject);
myObject.stack; // Similar to `new Error().stack`
The first line of the trace will be prefixed with
${myObject.name}: ${myObject.message}.
The optional constructorOpt argument accepts a function. If given, all frames
above constructorOpt, including constructorOpt, will be omitted from the
generated stack trace.
The constructorOpt argument is useful for hiding implementation
details of error generation from the user. For instance:
function a() {
b();
}
function b() {
c();
}
function c() {
// Create an error without stack trace to avoid calculating the stack trace twice.
const { stackTraceLimit } = Error;
Error.stackTraceLimit = 0;
const error = new Error();
Error.stackTraceLimit = stackTraceLimit;
// Capture the stack trace above function b
Error.captureStackTrace(error, b); // Neither function c, nor b is included in the stack trace
throw error;
}
a();
OptionalconstructorOpt: FunctionStaticprepare
Error thrown by the Result
unwrap*and Result.matchBad helpers when a result is the wrong variant for what was asked (e.g.unwrapon a Bad, orunwrapBadon an Ok). The message embeds the offending reason tag. These helpers are the deliberate escape hatch out of the type-safe flow.