Fixed broken delegation for global meterproviders (#5827)

[Jesse-Bonfire]

Fixed broken delegation for global meterproviders (#5827)

[linux-foundation-easycla]

• ❌ - login: @Jesse-Bonfire / name: Jesse Bank . The commit (7ff5cff) is not authorized under a signed CLA. Please click here to be authorized. For further assistance with EasyCLA, please submit a support request ticket.

[dashpole]

Can you add a unit test that fails before the fix, and passes after?

[dmathieu]

You will also need to sign the CLA.

[Jesse-Bonfire]

Working with my company to get CLA approval. Also where should I put the unit test? internal/global/meter_test.go or is there a better spot?

[dashpole]

internal/global/meter_test.go is great

[blkt]

Hello folks, sorry to jump in, @MrAlias kindly pointed me to this PR while discussing a problem I had with the recent release of opentelemetry.

While this fix indeed solves the broken delegation problem in our case, the setup we have had the system panicking because it went through this line of code which is not followed by a return like similar occurrences, like this and this.
As a result, it ran reg.Unregister with a null pointer.

Since the code has been there for a while I assume this is the desired behavior, but it does look suspicious to me, so I wanted to put this on your radar.