fix: Ensure config keys are printed for config errors

fixes #17960

package.json

@@ -67,7 +67,7 @@
     "@eslint-community/regexpp": "^4.6.1",
     "@eslint/eslintrc": "^3.0.0",
     "@eslint/js": "9.0.0-alpha.0",
-    "@humanwhocodes/config-array": "^0.11.13",
+    "@humanwhocodes/config-array": "^0.11.14",
     "@humanwhocodes/module-importer": "^1.0.1",
     "@nodelib/fs.walk": "^1.2.8",
     "ajv": "^6.12.4",

tests/bin/eslint.js

@@ -438,6 +438,21 @@ describe("bin/eslint.js", () => {
             });
         });
 
+        // https://github.com/eslint/eslint/issues/17960
+        it("should include key information in the error message when there is an invalid config", () => {
+
+            // The error message should include the key name
+            const config = path.join(__dirname, "../fixtures/bin/eslint.config-invalid-key.js");
+            const child = runESLint(["--config", config, "conf", "tools"]);
+            const exitCodeAssertion = assertExitCode(child, 2);
+            const outputAssertion = getOutput(child).then(output => {
+                assert.include(output.stderr, "Key \"linterOptions\": Key \"reportUnusedDisableDirectives\"");
+            });
+
+            return Promise.all([exitCodeAssertion, outputAssertion]);
+
+        });
+
         it("prints the error message pointing to line of code", () => {
             const invalidConfig = path.join(__dirname, "../fixtures/bin/eslint.config.js");
             const child = runESLint(["--no-ignore", "-c", invalidConfig]);

tests/fixtures/bin/eslint.config-invalid-key.js

@@ -0,0 +1,5 @@
+module.exports = [{
+    linterOptions: {
+        reportUnusedDisableDirectives: "banana"
+    }
+}];

tests/lib/config/flat-config-array.js

@@ -1043,7 +1043,7 @@ describe("FlatConfigArray", () => {
                                 reportUnusedDisableDirectives: {}
                             }
                         }
-                    ], /Expected one of: "error", "warn", "off", 0, 1, 2, or a boolean./u);
+                    ], /Key "linterOptions": Key "reportUnusedDisableDirectives": Expected one of: "error", "warn", "off", 0, 1, 2, or a boolean./u);
                 });
 
                 it("should merge two objects when second object has overrides", () => assertMergedResult([
@@ -2264,4 +2264,27 @@ describe("FlatConfigArray", () => {
         });
 
     });
+
+    describe("invalid options", () => {
+
+        it("should report key when an invalid option is found during merge", () => {
+            const configs = new FlatConfigArray([
+                {
+                    rules: {
+                    }
+                },
+                {
+                    linterOptions: {
+                        reportUnusedDisableDirectives: "foo"
+                    }
+                }
+            ]);
+
+            configs.normalizeSync();
+
+            assert.throws(() => {
+                configs.getConfig("foo.js");
+            }, /Key "linterOptions": Key "reportUnusedDisableDirectives":/u);
+        });
+    });
 });