Problem

linkml-lint's no_undeclared_ranges rule reports range 'None' is not defined on a slot whose range is expressed through any_of (or exactly_one_of) instead of a top-level range:, even though the boolean expression fully specifies the range.

classes:
  Foo:
    attributes:
      bar:
        any_of:
          - range: integer
          - range: string

$ linkml-lint test.yaml
  error    Class 'Foo' slot 'bar' range 'None' is not defined.  (no_undeclared_ranges)

Cause

SchemaView.slot_range_as_union(slot) returns the slot's own (unset) top-level range as None alongside the concrete ranges gathered from any_of/exactly_one_of — e.g. [None, 'integer', 'string']. The rule then checks None against the set of defined elements and flags it.

Fix

Drop the None entry from the range set only when the union also contains concrete ranges (i.e. when a boolean expression supplied them). This:

• removes the false positive for any_of/exactly_one_of slots,
• keeps flagging a genuinely undefined range named inside the expression (e.g. spreadsheet), now by its real name rather than as None,
• preserves the existing behaviour that a slot with no range at all and no default_range is still reported (covered by test_missing_default_range_undeclared_ranges).

Tests

Added parametrised (any_of/exactly_one_of) tests to test_rule_no_undeclared_ranges.py: one asserting no false positive when all expression ranges are defined, one asserting an undefined expression range is still flagged by name. Red before / green after; full linter suite passes (161).

Closes #3477.