Upgrade js-yaml from 4.x to 5.1.0

lib/parsers/yaml.ts

@@ -1,8 +1,6 @@
+import { JSON_SCHEMA, load } from "js-yaml";
+import type { FileInfo, Plugin } from "../types/index.js";
 import { ParserError } from "../util/errors.js";
-import yaml from "js-yaml";
-import { JSON_SCHEMA } from "js-yaml";
-import type { FileInfo } from "../types/index.js";
-import type { Plugin } from "../types/index.js";
 
 export default {
   /**
@@ -39,12 +37,17 @@ export default {
     }
 
     if (typeof data === "string") {
+      // Handle empty strings - js-yaml 5.x throws an error for empty input
+      if (data.trim() === "") {
+        return undefined;
+      }
+
       try {
-        return yaml.load(data, { schema: JSON_SCHEMA });
+        return load(data, { schema: JSON_SCHEMA });
       } catch {
         try {
           // fallback to non JSON_SCHEMA
-          return yaml.load(data);
+          return load(data);
         } catch (e: any) {
           throw new ParserError(e?.message || "Parser Error", file.url);
         }

package.json

@@ -72,13 +72,12 @@
     "@types/json-schema": "^7.0.15"
   },
   "dependencies": {
-    "js-yaml": "^4.2.0"
+    "js-yaml": "^5.1.0"
   },
   "devDependencies": {
     "@eslint/compat": "^2.1.0",
     "@eslint/js": "^10.0.1",
     "@types/eslint": "^9.6.1",
-    "@types/js-yaml": "^4.0.9",
     "@types/json-schema": "^7.0.15",
     "@types/node": "^25.9.3",
     "@typescript-eslint/eslint-plugin": "^8.61.0",

test/specs/bundle-null-value/bundled.ts

@@ -3,7 +3,7 @@ const bundledSchema = {
     Pet: {
       example: {
         breed: "dog",
-        name: null,
+        name: "",
       },
       properties: {
         breed: {

test/specs/invalid/invalid.spec.ts

@@ -128,7 +128,7 @@ describe("Invalid syntax", () => {
               name: ParserError.name,
               message: (message: any) =>
                 message.includes(
-                  "invalid.yaml: incomplete explicit mapping pair; a key node is missed; or followed by a non-tabulated empty line (1:1)",
+                  "invalid.yaml: unexpected end of the stream within a flow collection (2:1)",
                 ),
               path: [],
               source: (message: any) => message.endsWith("test/specs/invalid/invalid.yaml"),
@@ -269,7 +269,7 @@ describe("Invalid syntax", () => {
 
       // Because the JSON and YAML parsers were disabled, the invalid YAML file got parsed as plain text
       expect(schema).to.deep.equal({
-        foo: ":\n",
+        foo: "{ invalid yaml: [\n",
       });
     });
 
@@ -319,7 +319,7 @@ describe("Invalid syntax", () => {
               name: ParserError.name,
               message: (message: any) =>
                 message.includes(
-                  "invalid.yaml: incomplete explicit mapping pair; a key node is missed; or followed by a non-tabulated empty line (1:1)",
+                  "invalid.yaml: unexpected end of the stream within a flow collection (2:1)",
                 ),
               path: ["foo"],
               // source: message => message.endsWith("/test/") || message.startsWith("http://localhost"),
@@ -397,7 +397,7 @@ describe("Invalid syntax", () => {
           { foo: { $ref: path.rel("test/specs/invalid/invalid.yaml") } },
           { continueOnError: true, parse: { yaml: false, json: false } },
         );
-        expect(result).to.deep.equal({ foo: ":\n" });
+        expect(result).to.deep.equal({ foo: "{ invalid yaml: [\n" });
       });
     });
   });

test/specs/invalid/invalid.yaml

@@ -1 +1 @@
-:
+{ invalid yaml: [

test/specs/working-directory/nested/working-dir.spec.ts

@@ -1,10 +1,10 @@
+import fsp from "fs/promises";
+import { load } from "js-yaml";
 import { describe, expect, it } from "vitest";
 import $RefParser from "../../../../lib";
-import path from "../../../utils/path";
-import yaml from "js-yaml";
-import fsp from "fs/promises";
-import helper from "../../../utils/helper";
 import { JSONParserError } from "../../../../lib/util/errors";
+import helper from "../../../utils/helper";
+import path from "../../../utils/path";
 
 describe("Working directory", () => {
   it("should parse using the relative directory of the resolved file", async () => {
@@ -16,7 +16,7 @@ describe("Working directory", () => {
     const parser = new $RefParser();
     const schema = path.rel("test/specs/working-directory/api/example.yaml");
     const contents = await fsp.readFile(schema, "utf-8");
-    const parsed = await yaml.load(contents);
+    const parsed = await load(contents);
     try {
       await parser.dereference(parsed);
       helper.shouldNotGetCalled();