feat(core): better cause data extraction (#17375)

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- [x] If you've added code that should be tested, please add tests.
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---

closes #15142 

When using `ExtraErrorDataIntegration`, `error.cause` serializes with
`.toString()` which is not very informative considering the purpose of
the integration.

This PR improves `error.cause` handling in `ExtraErrorDataIntegration`
by recursing the `_extractErrorData` for a single cause depth. To match
the outer structure and provide more information the cause object is
wrapped with `[name]`.

The `.toString()` serialized data is gone now but if we are using
`LinkedErrorsIntegration` the string message will still be visible.

Since these changes are useful enough, I think more detailed
specifications (like cause recursion) could be addressed by future PRs -
open to suggestions.


**Before:**
```javascript
// error.cause was serialized as: "SyntaxError: bar"
{
  TypeError: {
    cause: "SyntaxError: bar"  // Just toString() output
  }
}
```

**After:**
```javascript
// error.cause now includes full error data extraction
{
  TypeError: {
    cause: {
      SyntaxError: {
        baz: 42,
        foo: "aaaa...a...",
      }
    }
  }
}
```

Author: ha1fstack

packages/core/src/integrations/extraerrordata.ts

@@ -115,7 +115,12 @@ function _extractErrorData(
     // Error.cause is a standard property that is non enumerable, we therefore need to access it separately.
     // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/cause
     if (captureErrorCause && error.cause !== undefined) {
-      extraErrorInfo.cause = isError(error.cause) ? error.cause.toString() : error.cause;
+      if (isError(error.cause)) {
+        const errorName = error.cause.name || error.cause.constructor.name;
+        extraErrorInfo.cause = { [errorName]: _extractErrorData(error.cause as ExtendedError, false, maxValueLength) };
+      } else {
+        extraErrorInfo.cause = error.cause;
+      }
     }
 
     // Check if someone attached `toJSON` method to grab even more properties (eg. axios is doing that)

packages/core/test/lib/integrations/extraerrordata.test.ts

@@ -55,9 +55,11 @@ describe('ExtraErrorData()', () => {
     });
   });
 
-  it('doesnt choke on linked errors and stringify names instead', () => {
+  it('should extract error data from the error cause with the same policy', () => {
     const error = new TypeError('foo') as ExtendedError;
-    error.cause = new SyntaxError('bar');
+    error.cause = new SyntaxError('bar') as ExtendedError;
+    error.cause.baz = 42;
+    error.cause.foo = 'a'.repeat(300);
 
     const enhancedEvent = extraErrorData.processEvent?.(
       event,
@@ -69,7 +71,12 @@ describe('ExtraErrorData()', () => {
 
     expect(enhancedEvent.contexts).toEqual({
       TypeError: {
-        cause: 'SyntaxError: bar',
+        cause: {
+          SyntaxError: {
+            baz: 42,
+            foo: `${'a'.repeat(250)}...`,
+          },
+        },
       },
     });
   });