Improve alert policy error handling

[jcardinal]

I found that attempting to import a team alert policy without specifying the team_id would crash the plugin without providing the user with useful feedback:

Stack trace from the terraform-provider-opsgenie_v0.6.34 plugin:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x60 pc=0x1034d0e04]

goroutine 30 [running]:
github.com/opsgenie/terraform-provider-opsgenie/opsgenie.resourceOpsGenieAlertPolicyRead({0x1037a2a60?, 0x140001191c0?}, 0x140005c6080, {0x10366d7c0?, 0x140001aaf90?})
	github.com/opsgenie/terraform-provider-opsgenie/opsgenie/resource_opsgenie_alert_policy.go:298 +0x424
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).read(0x140003c0a80, {0x1037a2a60, 0x140001191c0}, 0x24?, {0x10366d7c0, 0x140001aaf90})
	github.com/hashicorp/terraform-plugin-sdk/[email protected]/helper/schema/resource.go:358 +0xec
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).RefreshWithoutUpgrade(0x140003c0a80, {0x1037a2a60, 0x140001191c0}, 0x140002c4c30, {0x10366d7c0, 0x140001aaf90})
	github.com/hashicorp/terraform-plugin-sdk/[email protected]/helper/schema/resource.go:635 +0x30c
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*GRPCProviderServer).ReadResource(0x14000120750, {0x1037a2a60, 0x140001191c0}, 0x14000119240)
	github.com/hashicorp/terraform-plugin-sdk/[email protected]/helper/schema/grpc_provider.go:576 +0x3d8
github.com/hashicorp/terraform-plugin-go/tfprotov5/tf5server.(*server).ReadResource(0x1400011f180, {0x1037a2b08?, 0x140002b1500?}, 0x1400010cc60)
	github.com/hashicorp/[email protected]/tfprotov5/tf5server/server.go:553 +0x310
github.com/hashicorp/terraform-plugin-go/tfprotov5/internal/tfplugin5._Provider_ReadResource_Handler({0x10376dc40?, 0x1400011f180}, {0x1037a2b08, 0x140002b1500}, 0x1400010cc00, 0x0)
	github.com/hashicorp/[email protected]/tfprotov5/internal/tfplugin5/tfplugin5_grpc.pb.go:344 +0x174
google.golang.org/grpc.(*Server).processUnaryRPC(0x1400013c700, {0x1037a6910, 0x14000476000}, 0x140005ba200, 0x140003f6630, 0x103c29c70, 0x0)
	google.golang.org/[email protected]/server.go:1194 +0xaf0
google.golang.org/grpc.(*Server).handleStream(0x1400013c700, {0x1037a6910, 0x14000476000}, 0x140005ba200, 0x0)
	google.golang.org/[email protected]/server.go:1517 +0x840
google.golang.org/grpc.(*Server).serveStreams.func1.2()
	google.golang.org/[email protected]/server.go:859 +0x88
created by google.golang.org/grpc.(*Server).serveStreams.func1
	google.golang.org/[email protected]/server.go:857 +0x298

Error: The terraform-provider-opsgenie_v0.6.34 plugin crashed!

This is always indicative of a bug within the plugin. It would be immensely
helpful if you could report the crash with the plugin's maintainers so that it
can be fixed. The output above should help diagnose the issue.

We were handling 404's specifically, but ignoring other error types. I've added error handling for other error types and confirms it fixed my particular crash:

Planning failed. Terraform encountered an error while generating this plan.

╷
│ Error: Cannot import non-existent remote object
│
│ While attempting to import an existing object to "opsgenie_alert_policy.justinTest", the provider detected that no object
│ exists with the given id. Only pre-existing objects can be imported; check that the id is correct and that it is associated
│ with the provider's configured region or endpoint, or use "terraform apply" to create a new remote object for this resource.

I believe this will also resolve this issue.

As an aside, I introduced the pattern of using the tflog package for logging, instead of the log package. Terraform now recommends this pattern for logging, and it solves the issue I raised here, where filtering logs by level does not work correctly.

[koushik-swaminathan]

Hi @jcardinal, can you tell me exactly how to replicate this plugin crash? Whenever I try to run the import without team_id, I'm not getting a plugin crash, instead, I get this error:

Planning failed. Terraform encountered an error while generating this plan.
│ Error: Cannot import non-existent remote object
│
│ While attempting to import an existing object to "opsgenie_alert_policy.koushikTest", the provider detected that no object
│ exists with the given id. Only pre-existing objects can be imported; check that the id is correct and that it is associated
│ with the provider's configured region or endpoint, or use "terraform apply" to create a new remote object for this resource.

[jcardinal]

@koushik-swaminathan is it possible you're using an API key with global privileges? When I encountered the error, I was using an API key with team-level scope. I'm guessing the API returns a different error depending on whether the key allows the caller to know whether the given global ID exists.