SDK accepts and sends none-primitive values in `setTag`

[Lms24]

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/core

SDK Version

10.24.0

Framework Version

n/a

Link to Sentry event

n/a

Reproduction Example/SDK Setup

N/A

Steps to Reproduce

Sentry.setTag('tag_1', {foo: 'bar'})

Expected Result

Only tags with primitive values are sent. Object or array values should be discarded or stringified.

Actual Result

Tags with object/array values are sent

Additional Context

To be clear: Our type definitions allow only Primitive values. But in non-TS applications, users can pass in arbitrary data without necessarily being aware of this limitations.

We only document string values in our docs, so allowing primitives is already a superset here. But this seems to work well enough in the product.

However, I don't think we should send objects/arrays, etc. Especially, given that we had a test against that, which unfortunately didn't catch the violation (#18162)

_{Tip: React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.}

[linear]

JS-1148

[Lms24]

We seem to handle invalid tag data types in the product:

So this isn't the end of the world. But I'd rather avoid getting into this state in the first place.

[Lms24]

We decided that for now we don't "fix" this, primarily due to our type definitions already only accepting primitive values and Sentry handling invalid non-primitive values anyway. We can revisit if this becomes a problem.

See #18167 (review) and following comments for more context