✨ feat: Preserve AggregateError.errors even if showHidden is "none"

Author: Snowflyt

packages/lite/src/index.ts

@@ -737,13 +737,18 @@ function buildTree(
         )
           otherKeys.push(key);
       }
-      // Preserve Error.cause
-      if (
-        value instanceof Error &&
-        allKeys.indexOf("cause") !== -1 &&
-        otherKeys.indexOf("cause") === -1
-      )
-        otherKeys.push("cause");
+      const ensurePreservedKeys = [
+        // Error.cause
+        value instanceof Error && "cause",
+        // AggregateError.errors
+        // @ts-expect-error - AggregateError is only available in ES2021+
+        typeof AggregateError !== "undefined" &&
+          // @ts-expect-error - AggregateError is only available in ES2021+
+          value instanceof AggregateError &&
+          "errors",
+      ].filter((k) => k) as string[];
+      for (const key of ensurePreservedKeys)
+        if (allKeys.indexOf(key) !== -1 && otherKeys.indexOf(key) === -1) otherKeys.push(key);
 
       // Array element
       const arrayEntries: Node[] = arrayItemKeys.map((key) =>

packages/lite/test/error.spec.ts

@@ -243,7 +243,17 @@ describe("Error", () => {
       error = e;
     }
 
-    expect(show(error)).toMatch(/^AbortError: The operation was aborted.*?\n {4}at /);
+    expect(show(error)).toMatch(
+      /^AbortError: The operation was aborted.*?\n {4}at .+\[cause\]: Error: boom\n/s,
+    );
+    expect(inspect(error)).toEqual(util.inspect(error));
+    expect(inspect(error, { showHidden: true })).toEqual(util.inspect(error, { showHidden: true }));
+  });
+
+  it("should show AggregateError.errors by default", () => {
+    const error = new AggregateError([new Error("foo"), new TypeError("bar")], "baz");
+
+    expect(show(error)).toMatch(/^AggregateError: baz\n {4}at .+\[errors\]: \[/s);
     expect(inspect(error)).toEqual(util.inspect(error));
     expect(inspect(error, { showHidden: true })).toEqual(util.inspect(error, { showHidden: true }));
   });

src/index.ts

@@ -887,13 +887,18 @@ function buildTree(
         )
           otherKeys.push(key);
       }
-      // Preserve Error.cause
-      if (
-        value instanceof Error &&
-        allKeys.indexOf("cause") !== -1 &&
-        otherKeys.indexOf("cause") === -1
-      )
-        otherKeys.push("cause");
+      const ensurePreservedKeys = [
+        // Error.cause
+        value instanceof Error && "cause",
+        // AggregateError.errors
+        // @ts-expect-error - AggregateError is only available in ES2021+
+        typeof AggregateError !== "undefined" &&
+          // @ts-expect-error - AggregateError is only available in ES2021+
+          value instanceof AggregateError &&
+          "errors",
+      ].filter((k) => k) as string[];
+      for (const key of ensurePreservedKeys)
+        if (allKeys.indexOf(key) !== -1 && otherKeys.indexOf(key) === -1) otherKeys.push(key);
 
       // Array element
       const arrayEntries: Node[] = arrayItemKeys.map((key) =>

test/error.spec.ts

@@ -243,7 +243,17 @@ describe("Error", () => {
       error = e;
     }
 
-    expect(show(error)).toMatch(/^AbortError: The operation was aborted.*?\n {4}at /);
+    expect(show(error)).toMatch(
+      /^AbortError: The operation was aborted.*?\n {4}at .+\[cause\]: Error: boom\n/s,
+    );
+    expect(inspect(error)).toEqual(util.inspect(error));
+    expect(inspect(error, { showHidden: true })).toEqual(util.inspect(error, { showHidden: true }));
+  });
+
+  it("should show AggregateError.errors by default", () => {
+    const error = new AggregateError([new Error("foo"), new TypeError("bar")], "baz");
+
+    expect(show(error)).toMatch(/^AggregateError: baz\n {4}at .+\[errors\]: \[/s);
     expect(inspect(error)).toEqual(util.inspect(error));
     expect(inspect(error, { showHidden: true })).toEqual(util.inspect(error, { showHidden: true }));
   });