Bug: panic on SetMeterProvider

[sarathsp06]

Description

Panic on setting SetMeterProvider

Starting: /home/sarath/gopath/bin/dlv dap --listen=127.0.0.1:37125 --log-dest=3 from /home/sarath/projects/messageplusio/be/cmd/rest
DAP server listening at: 127.0.0.1:37125
Type 'dlv help' for list of commands.
2024/09/28 08:22:32 goose: no migrations to run. current version: 20240906210523
2024/09/28 08:22:32 goose: no migrations to run. current version: 20230711140249
2024/09/28 08:22:32 invalid observable: from different implementation
2024/09/28 08:24:41 failed to upload metrics: context deadline exceeded
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xb6295c]

goroutine 1 [running]:
go.opentelemetry.io/otel/internal/global.(*registration).setDelegate(0xc000450900, {0x1d97308, 0xc000494160})
	/home/sarath/gopath/pkg/mod/go.opentelemetry.io/otel@v1.30.0/internal/global/meter.go:492 +0x25c
go.opentelemetry.io/otel/internal/global.(*meter).setDelegate(0xc00019e090, {0x1d7c830, 0xc00011c960})
	/home/sarath/gopath/pkg/mod/go.opentelemetry.io/otel@v1.30.0/internal/global/meter.go:138 +0x2bc
go.opentelemetry.io/otel/internal/global.(*meterProvider).setDelegate(0xc0003ff080, {0x1d7c830, 0xc00011c960})
	/home/sarath/gopath/pkg/mod/go.opentelemetry.io/otel@v1.30.0/internal/global/meter.go:47 +0x1d4
go.opentelemetry.io/otel/internal/global.SetMeterProvider.func1()
	/home/sarath/gopath/pkg/mod/go.opentelemetry.io/otel@v1.30.0/internal/global/state.go:171 +0xad
sync.(*Once).doSlow(0x26a0d80, 0xc00059f1a0)
	/home/sarath/go/src/sync/once.go:76 +0x168
sync.(*Once).Do(0x26a0d80, 0xc00059f1a0)
	/home/sarath/go/src/sync/once.go:67 +0x3e
go.opentelemetry.io/otel/internal/global.SetMeterProvider({0x1d7c830, 0xc00011c960})
	/home/sarath/gopath/pkg/mod/go.opentelemetry.io/otel@v1.30.0/internal/global/state.go:169 +0x22d
go.opentelemetry.io/otel.SetMeterProvider({0x1d7c830, 0xc00011c960})
	/home/sarath/gopath/pkg/mod/go.opentelemetry.io/otel@v1.30.0/metric.go:41 +0x1d
github.com/messageplusio/be/pkg/telemetry.InitMeterProvider({0x1d85558, 0x26a06c0})
	/home/sarath/projects/messageplusio/be/pkg/telemetry/telemetry.go:63 +0x2e5
main.main()
	/home/sarath/projects/messageplusio/be/cmd/rest/main.go:86 +0xb59
Process 249736 has exited with status 2
Detaching

Explanation

If RegisterCallback fails with an error then reg would be nil and unusable. Trying derefer reg for reg.Unregister would panic

Fix : #5851

Environment

Applicable on any env

• OS: Fedora
• Architecture: x86
• Go Version: 1.23.1
• opentelemetry-go version: v1.30.0

Expected behavior

No panic

[MrAlias]

This looks like a duplicate of #5827