Enum PathError 

pub enum PathError {
    UndefinedRoot(String),
    Absence(String),
    Shape(String),
}

Why a variable path failed to resolve.

The three-way split is load-bearing for ${path:-default} (decision A): the default fires on absence but never on a shape error — a wrong-typed access is a bug, not a missing value. All three are loud for a bare access; they diverge only when :- is present (see the default handling), where UndefinedRoot/Absence yield the default and Shape still shouts.

• UndefinedRoot — the root variable (or an unset dynamic $k subscript) is not in scope. Soft in string interpolation (expands to empty, matching bash), loud in expression position.
• Absence — the path is well-shaped but the target isn’t there: a missing record key or an out-of-bounds list index.
• Shape — the access is wrong for the value: a string key on a list, an integer index on a record, subscripting a scalar, a dotted (non-bracket) segment, or slicing a record. Never suppressed by :-.

A loud error is surfaced everywhere, including inside strings; it is NEVER silently swallowed to an empty expansion.

Variants

UndefinedRoot(String)

The root variable is not in scope (or an unset dynamic $k subscript).

Absence(String)

A missing key or out-of-bounds index — absence, not misuse.

Shape(String)

A wrong-for-the-shape access. Message ready to display.

Trait Implementations

impl Clone for PathError

fn clone(&self) -> PathError

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PathError

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

Formats the value using the given formatter.

impl PartialEq for PathError

fn eq(&self, other: &PathError) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for PathError