readFromJsonFile not working? about php-openapi HOT 4 CLOSED

Fatal error: Uncaught TypeError: Argument 1 passed to cebe\openapi\ReferenceContext::resolveRelativeUri() must be of the type string, null given, called in /tmp/test/vendor/cebe/php-openapi/src/spec/Reference.php on line 139 and defined in /tmp/test/vendor/cebe/php-openapi/src/ReferenceContext.php on line 77

TypeError: Argument 1 passed to cebe\openapi\ReferenceContext::resolveRelativeUri() must be of the type string, null given, called in /tmp/test/vendor/cebe/php-openapi/src/spec/Reference.php on line 139 in /tmp/test/vendor/cebe/php-openapi/src/ReferenceContext.php on line 77

Call Stack:
    0.0001     360784   1. {main}() /tmp/test/test.php:0
    0.0009     453776   2. cebe\openapi\Reader::readFromJsonFile() /tmp/test/test.php:7
    0.9087    4320888   3. cebe\openapi\spec\OpenApi->resolveReferences() /tmp/test/vendor/cebe/php-openapi/src/Reader.php:72
    0.9088    4320888   4. cebe\openapi\spec\Paths->resolveReferences() /tmp/test/vendor/cebe/php-openapi/src/SpecBaseObject.php:295
    0.9256    4183648   5. cebe\openapi\spec\PathItem->resolveReferences() /tmp/test/vendor/cebe/php-openapi/src/spec/Paths.php:228
    0.9256    4183648   6. cebe\openapi\spec\Operation->resolveReferences() /tmp/test/vendor/cebe/php-openapi/src/SpecBaseObject.php:295
    0.9256    4183648   7. cebe\openapi\spec\RequestBody->resolveReferences() /tmp/test/vendor/cebe/php-openapi/src/SpecBaseObject.php:295
    0.9256    4183648   8. cebe\openapi\spec\MediaType->resolveReferences() /tmp/test/vendor/cebe/php-openapi/src/SpecBaseObject.php:301
    0.9256    4183648   9. cebe\openapi\spec\Reference->resolve() /tmp/test/vendor/cebe/php-openapi/src/SpecBaseObject.php:293
    0.9256    4183648  10. cebe\openapi\ReferenceContext->resolveRelativeUri() /tmp/test/vendor/cebe/php-openapi/src/spec/Reference.php:139