[BUG]: playground can't handle messages with lists of content blocks

[axiomofjoy]

Where do you use Phoenix

Local (self-hosted)

What version of Phoenix are you using?

latest

What operating system are you seeing the problem on?

MacOS

What version of Python are you running Phoenix with?

3.11

What version of Python or Node are you using instrumentation with?

n/a

What instrumentation are you using?

openinference-instrumentation-openai-agents

What happened?

AI message content is empty when the attributes contain a list of content blocks.

What did you expect to happen?

Message content should display.

How can we reproduce the bug?

Run openinference-instrumentation-openai-agents instrumentation.

Additional information

No response