Illegal operation on a directory

[adamaltman]

If someone accidentally made a $ref that points to a directory instead of a file, it will result in an unfriendly error.

(node:30324) UnhandledPromiseRejectionWarning: Error: EISDIR: illegal operation on a directory, read
    at Object.readSync (fs.js:564:3)
    at tryReadSync (fs.js:353:20)
    at Object.readFileSync (fs.js:390:19)
    at resolve (/Users/adam/Projects/Rebilly/api-definitions/node_modules/@redocly/openapi-cli/dist/resolver.js:88:28)
    at resolveNode (/Users/adam/Projects/Rebilly/api-definitions/node_modules/@redocly/openapi-cli/dist/resolver.js:231:28)
    at onNodeEnter (/Users/adam/Projects/Rebilly/api-definitions/node_modules/@redocly/openapi-cli/dist/traverse.js:92:35)
    at traverseNode (/Users/adam/Projects/Rebilly/api-definitions/node_modules/@redocly/openapi-cli/dist/traverse.js:112:29)
    at traverseChildren (/Users/adam/Projects/Rebilly/api-definitions/node_modules/@redocly/openapi-cli/dist/traverse.js:49:33)
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at async traverseNode (/Users/adam/Projects/Rebilly/api-definitions/node_modules/@redocly/openapi-cli/dist/traverse.js:140:30)
(node:30324) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)
(node:30324) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

[adamaltman]

This is solved by #146

[4] issue-145.yaml:21:11 at #/paths/~1/post/responses/200

Can't resolve $ref: EISDIR: illegal operation on a directory, read

19 | responses:
20 |   200:
21 |     $ref: "../"
   |     ^^^^^^^^^^^
22 | tags:
23 |   - Testing

Error was generated by the no-unresolved-refs rule.