TypeError: Cannot read properties of null when filter predicate evaluates a property on a null node

[Sruthisreem]

Summary

Spectral crashes with an unhandled TypeError when a ruleset uses a JSONPath filter predicate that reads a property of @, and the document contains a null value at a position the filter walks over. The whole lint run aborts; no diagnostics are returned.

The underlying issue appears to be in Nimma's filter-predicate codegen — @.foo is emitted without guarding against @ being null/undefined. Other JSONPath engines (jsonpath-plus, jsonpath-ng) return "no match" in this situation rather than throwing.

Steps to reproduce

api.yaml:

openapi: 3.0.0
info:
  title: Repro
  version: 1.0.0
paths:
  /foo:
    get:
      responses:
        '200':
          description: ok
          content:
            application/json:
              schema:
                type: object
                properties:
                  bar:
                    type: string
                    nullable: true
                    example: null

.spectral.yaml:

rules:
  date-format-required:
    given: "$..[?(@.format == 'date')]"
    severity: warn
    then:
      function: truthy

Run:

npx @stoplight/spectral-cli lint api.yaml --ruleset .spectral.yaml

Expected

Either:

• The filter predicate evaluates to false for the null node and the rule runs to completion (consistent with other JSONPath implementations), or
• A structured diagnostic is returned describing which rule/path failed, instead of an unhandled exception that aborts the entire run.

Actual

Error running Spectral!
Use --verbose flag to print the error stack.
Error #1: Cannot read properties of null (reading 'format')

Also reproduces in a Web Worker context

Same ruleset + spec loaded into a browser-side worker using @stoplight/spectral-core directly (no CLI) produces the same exception:

This rules out the CLI as the source — it's the core engine.

Why this matters

• The ruleset is structurally valid (passes assertValidRuleset and bundles cleanly).
• The spec is valid (null is a legal value for nullable: true properties, and is a legitimate example/default/enum value).

Environment

• @stoplight/spectral-cli: 6.16.0
• @stoplight/spectral-core: 1.23.0
• Node: 24.15.0
• OS: macOS

Related

• Spectral parsing chokes on unexpected null values #1981 — Spectral parsing chokes on unexpected null values
• spectral v6 linting chokes on empty object property example #2139 — v6 chokes on empty example (closed; workaround was "don't use empty example")
• Example value as null fails #2649 — Example value as null fails

These share the "null hostility" theme but are surfaced through different code paths. This report is specifically about Nimma's filter-predicate evaluator throwing on null @.

[slegarraga]

The root cause is upstream in Nimma's filter codegen: a predicate like ?(@.foo) compiles to a non-optional sandbox.value.foo, which throws when @ is null/undefined (e.g. example: null), aborting the whole query.

Opened a fix at P0lip/nimma#17 — optional chaining for filter member access (sandbox.value?.foo), so a null @ evaluates to a no-match instead of throwing, plus a regression test. Bumping nimma here once it's released should resolve this.

[sseelmann]

Also reproduces with the built-in spectral:oas ruleset (no custom rule), so it breaks default OpenAPI linting whenever a spec contains a null value. Here the offending filter is the enum rules' @.enum (duplicated-entry-in-enum / typed-enum), same null-guard gap you identified.

Minimal repro.

openapi.yaml:

openapi: 3.0.3
info:
  title: Null crash repro
  version: 1.0.0
paths: {}
components:
  schemas:
    Thing:
      type: object
      properties:
        foo:
          type: string
      example:
        foo: null

.spectral.yaml:

extends: ["spectral:oas"]

Run:

spectral lint -r .spectral.yaml openapi.yaml

• 6.15.0: lints fine (reports oas3-valid-schema-example on example.foo)
• 6.16.2 (:latest): Error #1: Cannot read properties of null (reading 'enum'), and the whole run aborts with no findings

Workaround: disable duplicated-entry-in-enum + typed-enum, or pin stoplight/spectral:6.15.0.