errors: avoid [object Object] as cause + fix ForwardedError name

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/errors/src/errors/CustomErrorBase.ts

@@ -29,6 +29,11 @@ export class CustomErrorBase extends Error {
       if (isError(cause)) {
         assignedCause = cause;
         causeStr = String(cause);
+
+        // Prefer the cause.toString, but if it's not implemented we use a nicer fallback
+        if (causeStr === '[object Object]') {
+          causeStr = `${cause.name}: ${cause.message}`;
+        }
       } else {
         causeStr = `unknown error '${cause}'`;
       }

packages/errors/src/errors/common.test.ts

@@ -31,12 +31,26 @@ describe('common', () => {
 
   it('supports causes', () => {
     const cause = new Error('hello');
-    for (const [name, E] of Object.entries(errors)) {
+    const { ForwardedError, ...otherErrors } = { ...errors };
+    for (const [name, E] of Object.entries(otherErrors)) {
       const error = new E('abcdef', cause);
       expect(error.cause).toBe(cause);
       expect(error.toString()).toContain(
         `${name}: abcdef; caused by Error: hello`,
       );
     }
+
+    const error = new ForwardedError('abcdef', cause);
+    expect(error.cause).toBe(cause);
+    expect(error.toString()).toContain('Error: abcdef; caused by Error: hello');
+  });
+
+  it('avoids [object Object]', () => {
+    const cause = { name: 'SillyError', message: 'oh no' };
+    const error = new errors.ForwardedError('abcdef', cause);
+    expect(error.cause).toBe(cause);
+    expect(String(error)).toBe(
+      'SillyError: abcdef; caused by SillyError: oh no',
+    );
   });
 });

packages/errors/src/errors/common.ts

@@ -86,6 +86,6 @@ export class ForwardedError extends CustomErrorBase {
   constructor(message: string, cause: Error | unknown) {
     super(message, cause);
 
-    this.name = isError(cause) ? this.constructor.name : 'Error';
+    this.name = isError(cause) ? cause.name : 'Error';
   }
 }