[BUG] Core issue with Sentry tracing

[KristofDeTroch]

Describe the Bug

When running a Mastra agent in an environment with Sentry for error monitoring the interop crashes on tracing interactions. It is not possible to disable tracing in Mastra and overriding it with a dummy handler results in not getting any responses and no api calls being made.
This is the dummy config we built:

const response = await this.proposalAgent.generate([{ role: 'user', content }], {
      telemetry: {
        isEnabled: true,
        tracer: {
          startActiveSpan: () => ({}) as any,
          startSpan: () => ({}) as any,
        },
      },
      output: dailyBriefItemSchema,
      maxRetries: config.genAi.maxRetries,
});

The error we get is:

The sentry source where this fails can be found in: https://github.com/getsentry/sentry-javascript/blob/5c4cab7b34c736ecd5c029048ba14181dabaaa9f/packages/opentelemetry/src/propagator.ts

Full thread can be found in discord: https://discord.com/channels/1309558646228779139/1350044378357563415

Steps To Reproduce

We added an example gist here: https://gist.github.com/ljobse/ca4fe4cc404c881782e51922d64cd428

Expected Behavior

1. Disabling tracing should not break behaviour
2. Interop with Sentry would be nice

Environment Information

@mastra/core@0.4.4
Node@20.12.0

Component

Integrations

Code Snippet

Error Logs

Additional Context

No response

Verification

• I have searched the existing issues to make sure this is not a duplicate
• I have included sufficient information for the team to reproduce and understand the issue

[ljobse]

I've been looking into this and have 1 very bad workaround:
Initializing sentry with skipOpenTelemetrySetup: true, will skip the invalid spans from being picked up. Obviously this will also drop all other spans so tracing will no longer work correctly in sentry.

I think there are 2 major issues here:

1. Disabling tracing does not actually disable any collection of spans. This is due to the decorator setup and the global telemetry configuration
2. Invalid spans are being registered. I think this is due to BaggageTracer but I don't really see why the opentelemetry data is structured differently from what sentry expects.

[TylerBarnes]

@wardpeet tagging you in since I believe you know about our telemetry setup

[Michielnuyts]

Running into the same issue at the moment. (0.7.0)