Enum EnvironmentError 

#[non_exhaustive]
pub enum EnvironmentError {
    InvalidAction(String),
    RenderFailed(String),
    IoError(Error),
    Config(ConfigError),
    StepAfterEpisodeEnd {
        status: EpisodeStatus,
    },
}

Error type for environment operations.

EnvironmentError captures failures that can occur during environment initialization, reset, or stepping. It provides detailed error messages and supports error chaining via the standard std::error::Error trait.

The enum is #[non_exhaustive]: downstream match expressions must carry a wildcard arm, so a future variant is not a breaking change.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

InvalidAction(String)

An invalid or out-of-bounds action was provided.

RenderFailed(String)

Rendering or display failed.

IoError(Error)

An I/O operation failed (wraps std::io::Error).

Config(ConfigError)

A configuration-domain invariant failed during a lifecycle operation.

A reset() may re-run construction-time work (e.g. rebuilding a procedural world), so a config-domain invariant — a ConfigError — can surface at reset, not only at construction. This variant is kept generic (not tied to any one environment) so any lifecycle method that re-validates config-domain state can propagate the failure with ?, avoiding a stringly-typed re-wrap.

StepAfterEpisodeEnd

step() was called after the episode already ended.

The action itself was legal; the call sequence was not. An episode that has emitted a snapshot with Snapshot::is_done == true is over — the only valid next lifecycle call is Environment::reset. Stepping again would silently resurrect a finished episode (re-entering the MDP from a terminal state, emitting rewards on a Running snapshot), so it is an error rather than a no-op.

The variant carries the EpisodeStatus that ended the episode, so the caller can distinguish an intrinsic MDP termination (EpisodeStatus::Terminated) from a wrapper-imposed truncation (EpisodeStatus::Truncated).

Fields

status: EpisodeStatus

The status that ended the episode (Terminated or Truncated).

Trait Implementations

impl Debug for EnvironmentError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for EnvironmentError

fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for EnvironmentError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<ConfigError> for EnvironmentError

fn from(source: ConfigError) -> Self

Converts to this type from the input type.

impl From<Error> for EnvironmentError

fn from(source: Error) -> Self

Converts to this type from the input type.