Skip to content

E_VAL_002 — Invalid argument to a binding constructor or function

A value passed into a flox binding fell outside the accepted range. Common cases:

  • A latency model was constructed with a negative mean, stddev, or sample value.
  • An EmpiricalLatency was constructed with all three sample arrays empty.
  • A tape diff or other I/O-bound function received a path that is not a directory.

The exception message includes the field name and the bad value.

How to fix

Inspect the failing call site and clamp or replace the offending value before construction. A negative latency mean is almost always a unit-conversion bug; an empty empirical sampler usually means the calibration step ran on no data.

from flox_py.latency_models import GaussianLatency

# Bad — stddev cannot be negative.
# GaussianLatency(feed_mean_ns=1000, feed_stddev_ns=-200, seed=42)

# Good.
GaussianLatency(feed_mean_ns=1000, feed_stddev_ns=200, seed=42)

const flox = require('@flox-foundation/flox');

// Bad — feedNs cannot be negative.
// new flox.ConstantLatency({ feedNs: -1 });

// Good.
new flox.ConstantLatency({ feedNs: 100 });

Common causes

  • A microsecond value passed where nanoseconds are expected, then multiplied wrong and ending up negative.
  • An empirical sampler initialised before any samples have been recorded.
  • A typo passing the wrong field as the stddev (e.g. -1 as a sentinel "unset" value).

See also