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fix(browser): Add a synthetic stack trace to DOMException with empty stack traces if attachStacktrace is true #19988

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fix(browser): Add a synthetic stack trace to DOMException with empty stack traces if attachStacktrace is true #19988

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029e8ff
fix(browser): Add a synthetic stack trace to DOMException with empty …
abcang Mar 26, 2026
c26f7a3
Run yarn format
abcang Mar 31, 2026
6503544
Merge branch 'develop' into abcang/add_synthetic_stack_trace_to_dom_e…
andreiborza May 12, 2026
83ae1e5
test(browser): cover empty DOMException stack type
logaretm May 12, 2026
901e3ef
test(browser): allow synthetic stack on DOMException regression
logaretm May 12, 2026
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2 changes: 1 addition & 1 deletion packages/browser/src/eventbuilder.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -288,7 +288,7 @@ export function eventFromUnknownInput(
if (isDOMError(exception) || isDOMException(exception as DOMException)) {
const domException = exception as DOMException;

if ('stack' in (exception as Error)) {
if ((exception as Error).stack) {
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@logaretm logaretm May 12, 2026

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h: I think this will change how the dom exceptions are classified, I pushed a test to see if it would pass.

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@logaretm logaretm May 12, 2026

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Maybe something like this would keep the best of both worlds here, could you try something like:

// same check as before
if ('stack' in (exception as Error)) {
  event = eventFromError(stackParser, exception as Error);

  // preserves the classification while adding stacktraces if it exists...
  const firstException = event.exception?.values?.[0];
  if (attachStacktrace && syntheticException && firstException && !firstException.stacktrace) {
    const frames = parseStackFrames(stackParser, syntheticException);
    if (frames.length) {
      firstException.stacktrace = { frames };
      addExceptionMechanism(event, { synthetic: true });
    }
  }
} else {
  // existing fallback
}

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@cursor cursor Bot May 12, 2026

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DOMException type classification lost for empty stack traces

Medium Severity

Changing the check from 'stack' in (exception as Error) to a truthy check causes DOMExceptions with empty stack strings to fall into the else branch, which uses eventFromString + addExceptionTypeValue. This loses the specific DOMException type (e.g., 'SyntaxError', 'NotAllowedError') and replaces it with a generic 'Error' type, because addExceptionTypeValue defaults the type to 'Error'. The exception value also changes from just the message to a name: message format. This regression in error classification will affect how users group and identify DOMException errors in Sentry. The contradictory test at line 190 (expecting type: 'SyntaxError') confirms this is a recognized problem — it will fail because the code actually produces type: 'Error'.

Additional Locations (1)
Fix in Cursor Fix in Web

Reviewed by Cursor Bugbot for commit 901e3ef. Configure here.

event = eventFromError(stackParser, exception as Error);
} else {
const name = domException.name || (isDOMError(domException) ? 'DOMError' : 'DOMException');
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85 changes: 85 additions & 0 deletions packages/browser/test/eventbuilder.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,91 @@
},
});
});

it('add a synthetic stack trace to DOMException with empty stack traces if attachStacktrace is true', async () => {
const exception = new DOMException('The string did not match the expected pattern.', 'SyntaxError');
exception.stack = '';

const syntheticException = new Error('Test message');
const event = await eventFromUnknownInput(defaultStackParser, exception, syntheticException, true);
expect(event.exception?.values?.[0]).toEqual(
expect.objectContaining({
mechanism: { handled: true, synthetic: true, type: 'generic' },
stacktrace: {
frames: expect.arrayContaining([expect.any(Object), expect.any(Object)]),
},
type: 'Error',
value: 'SyntaxError: The string did not match the expected pattern.',
}),
);
});

it('preserves DOMException type when stack is an empty string', () => {
const exception = new DOMException('The string did not match the expected pattern.', 'SyntaxError');
exception.stack = '';

const event = eventFromUnknownInput(defaultStackParser, exception, new Error('synthetic'), true);

expect(event.exception?.values?.[0]).toMatchObject({

Check failure on line 196 in packages/browser/test/eventbuilder.test.ts

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GitHub Actions / Browser Unit Tests

test/eventbuilder.test.ts > eventFromUnknownInput > preserves DOMException type when stack is an empty string 

AssertionError: expected { …(4) } to match object { type: 'SyntaxError', …(1) }
(6 matching properties omitted from actual)

- Expected
+ Received

  {
-   "type": "SyntaxError",
-   "value": "The string did not match the expected pattern.",
+   "type": "Error",
+   "value": "SyntaxError: The string did not match the expected pattern.",
  }

 ❯ test/eventbuilder.test.ts:196:42
type: 'SyntaxError',
value: 'The string did not match the expected pattern.',
});
});
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@cursor cursor Bot May 12, 2026

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Contradictory test expects wrong branch behavior

Medium Severity

The test "preserves DOMException type when stack is an empty string" expects type: 'SyntaxError' and value: 'The string did not match the expected pattern.', but it has the same setup as the test at line 172 (stack = '', attachStacktrace = true), which expects type: 'Error' and value: 'SyntaxError: The string did not match the expected pattern.'. Tracing through the production code, the empty stack takes the eventFromString path, producing type: 'Error' and the combined name: message value. This test's expectations reflect the old eventFromError path behavior and will fail.

Additional Locations (1)
Fix in Cursor Fix in Web

Reviewed by Cursor Bugbot for commit 83ae1e5. Configure here.

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@logaretm logaretm May 12, 2026

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This works against today's implementation, I'm just ensuring we lock it in and see if this PR changes it.


it('add a synthetic stack trace to DOMException without a stack traces property if attachStacktrace is true', async () => {
const exception = new DOMException('The string did not match the expected pattern.', 'SyntaxError');
delete exception.stack;

const syntheticException = new Error('Test message');
const event = await eventFromUnknownInput(defaultStackParser, exception, syntheticException, true);
expect(event.exception?.values?.[0]).toEqual(
expect.objectContaining({
mechanism: { handled: true, synthetic: true, type: 'generic' },
stacktrace: {
frames: expect.arrayContaining([expect.any(Object), expect.any(Object)]),
},
type: 'Error',
value: 'SyntaxError: The string did not match the expected pattern.',
}),
);
});

it("doesn't add a synthetic stack trace to DOMException with empty stack traces if attachStacktrace is false", async () => {
const exception = new DOMException('The string did not match the expected pattern.', 'SyntaxError');
exception.stack = '';

const syntheticException = new Error('Test message');
const event = await eventFromUnknownInput(defaultStackParser, exception, syntheticException, false);
expect(event.exception?.values?.[0]).toEqual({
type: 'Error',
value: 'SyntaxError: The string did not match the expected pattern.',
});
});

it("doesn't add a synthetic stack trace to DOMException with stack traces if attachStacktrace is true", async () => {
const exception = new DOMException('The string did not match the expected pattern.', 'SyntaxError');
exception.stack = 'SyntaxError\n at <anonymous>:1:2';

const syntheticException = new Error('Test message');
const event = await eventFromUnknownInput(defaultStackParser, exception, syntheticException, true);
expect(event.exception?.values?.[0]).toEqual(
expect.objectContaining({
stacktrace: {
frames: [
{
colno: 2,
filename: '<anonymous>',
function: '?',
in_app: true,
lineno: 1,
},
],
},
type: 'SyntaxError',
value: 'The string did not match the expected pattern.',
}),
);
});
});

describe('extractMessage', () => {
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