ReadonlycauseReadonlyderivedReadonlykindDiscriminated tag for exhaustive matching.
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
Raised when a derived's
compute(get)body itselfthrows a host error during (re)computation — the caller's own error, not an engine verdict.Remarks
A derived value is
derived(t) = f(b₁(t), …, bₙ(t)); if the user'sfthrows, the commit that triggered the recompute is aborted. Before this typed wrapper existed the two backends DIVERGED at the FFI seam: the TS floor rethrew the caller's raw error object out ofcommit, while the wasm engine flattened the throw toEngine(ComputeThrew { reason })and re-threw an unrelatedErrorcarrying only the stringified message — socatch (e) { if (e instanceof CauslError) }(and any branch one.cause) silently stopped working once wasm preloaded (causl-client#120).This error unifies the two: a user compute throw surfaces as the SAME
CauslErrorsubclass on both engines, carrying the ORIGINAL thrown value ascause(perError.cause's ES2022 contract) so adopters cane.cause instanceof MyValidationErrorto branch on their own error modes. On the wasm engine the derived compute lambda runs in JS behind the__causl_computeFFI crossing, so the real thrown object is captured host-side and preserved ascausewithout a Rust wire change.Engine-emitted typed errors raised THROUGH a compute (e.g. an unresolvable dynamic read → UndeclaredDependencyError, or a CycleError) are NOT wrapped by this class — they are already CauslErrors and pass through untouched (see asDerivedComputeError), so their specific identity is retained on both backends.
Param: derivedId
The derived node whose compute threw.
Param: cause
The original value the compute body threw.