PlanResourceChange panic: can't use ElementIterator on null value

[VenelinMartinov]

What happened?

During PlanResourceChange testing, the following error was discovered:

pulumi-fastly paniced during preview on one of the resource with the above error

pulumi/pulumi-fastly#536

Example

+ fastly:index/serviceVcl:ServiceVcl: (create)
          [urn=urn:pulumi:p-it-fv-az1205--service-5df87b39::fastly-service-v1::fastly:index/serviceVcl:ServiceVcl::demo]
          [provider=urn:pulumi:p-it-fv-az1205--service-5df87b39::fastly-service-v1::pulumi:providers:fastly::default_8_8_0_alpha_1715612702_cf498c3::04da6b54-80e4-46f7-96ec-b56ff0331ba9]
          activate       : true
          backends       : [
              [0]: {
                  address            : "127.0.0.1"
                  autoLoadbalance    : false
                  betweenBytesTimeout: 10000
                  connectTimeout     : 1000
                  errorThreshold     : 0
                  firstByteTimeout   : 15000
                  healthcheck        : ""
                  maxConn            : 200
                  maxTlsVersion      : ""
                  minTlsVersion      : ""
                  name               : "localhost"
                  overrideHost       : ""
                  port               : 80
                  requestCondition   : ""
                  shareKey           : ""
                  shield             : ""
                  sslCaCert          : ""
                  sslCertHostname    : ""
                  sslCheckCert       : true
                  sslCiphers         : ""
                  sslClientCert      : [secret]
                  sslClientKey       : [secret]
                  sslSniHostname     : ""
                  useSsl             : false
                  weight             : 100
              }
          ]
          comment        : "Managed by Terraform"
          defaultTtl     : 3600
          domains        : [
              [0]: {
                  comment   : "demo"
                  name      : "demo.pulumi3.io"
              }
          ]
          forceDestroy   : true
          http3          : false
          name           : "demo-842ce34"
          staleIfError   : false
          staleIfErrorTtl: 43200
  panic: can't use ElementIterator on null value
  
  goroutine 41 [running]:
  
  github.com/hashicorp/go-cty/cty.Value.ElementIterator({{{0x16cb9f0?, 0xc00012d4e0?}}, {0x0?, 0x0?}})
  
  	/home/runner/go/pkg/mod/github.com/hashicorp/go-cty@v1.4.1-0.20200414143053-d3edf31b6320/cty/value_ops.go:1038 +0xbe
  
  github.com/hashicorp/go-cty/cty.Value.AsValueSet({{{0x16cb9f0?, 0xc00012d4e0?}}, {0x0?, 0x0?}})
  
  	/home/runner/go/pkg/mod/github.com/hashicorp/go-cty@v1.4.1-0.20200414143053-d3edf31b6320/cty/value_ops.go:1270 +0xed
  
  github.com/fastly/terraform-provider-fastly/fastly.resourceService.validateUniqueNames.func11({0x16cb830?, 0xc0002f2240?}, 0x0?, {0x11cf9a0?, 0xc000124808?})
  
  	/home/runner/work/pulumi-fastly/pulumi-fastly/upstream/fastly/base_fastly_service.go:177 +0x11f
  
  github.com/fastly/terraform-provider-fastly/fastly.resourceService.All.func13({0x16cb830, 0xc0002f2240}, 0x14975ab?, {0x11cf9a0, 0xc000124808})
  
  	/home/runner/go/pkg/mod/github.com/pulumi/terraform-plugin-sdk/v2@v2.0.0-20240229143312-4f60ee4e2975/helper/customdiff/compose.go:52 +0xd2
  
  github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.schemaMap.Diff(0xc000445ce0, {0x16cb830, 0xc0002f2240}, 0xc0007a6ea0, 0xc0005823c0, 0xc00062b460, {0x11cf9a0, 0xc000124808}, 0x0)
  
  	/home/runner/go/pkg/mod/github.com/pulumi/terraform-plugin-sdk/v2@v2.0.0-20240229143312-4f60ee4e2975/helper/schema/schema.go:698 +0x4b4
  
  github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).SimpleDiff(0x16cba60?, {0x16cb830?, 0xc0002f2240?}, 0xc0007a6ea0, 0x12[93](https://github.com/pulumi/pulumi-fastly/actions/runs/9065253482/job/24906248746?pr=536#step:22:95)ce0?, {0x11cf9a0?, 0xc000124808?})
  
  	/home/runner/go/pkg/mod/github.com/pulumi/terraform-plugin-sdk/v2@v2.0.0-20240229143312-4f60ee4e2975/helper/schema/resource.go:967 +0xd5
  
  github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*GRPCProviderServer).PlanResourceChangeExtra(0xc0006221f8, {0x16cb830?, 0xc0002031d0?}, 0xc0007c1288)
  
  	/home/runner/go/pkg/mod/github.com/pulumi/terraform-plugin-sdk/v2@v2.0.0-20240229143312-4f60ee4e2975/helper/schema/grpc_provider.go:831 +0x9b6
  
  github.com/pulumi/pulumi-terraform-bridge/v3/pkg/tfshim/sdk-v2.(*grpcServer).PlanResourceChange(0xc000125200, {0x16cb830, 0xc0002031d0}, {0x149dfa5, 0x12}, {{0x16cba60?, 0xc00007ef40?}}, {{{0x16cba60, 0xc0001248e8}}, {0x1293ce0, ...}}, ...)
  
  	/home/runner/go/pkg/mod/github.com/pulumi/pulumi-terraform-bridge/v3@v3.82.1-0.20240513144526-3242c866b548/pkg/tfshim/sdk-v2/provider2.go:437 +0x41c
  
  github.com/pulumi/pulumi-terraform-bridge/v3/pkg/tfshim/sdk-v2.(*planResourceChangeImpl).Diff(0xc000629f80, {0x16cb830, 0xc0002031d0}, {0x149dfa5, 0x12}, {0x0?, 0x0?}, {0x16bd900?, 0xc000582050?}, {0x0, ...})
  
  	/home/runner/go/pkg/mod/github.com/pulumi/pulumi-terraform-bridge/v3@v3.82.1-0.20240513144526-3242c866b548/pkg/tfshim/sdk-v2/provider2.go:159 +0x371
  
  github.com/pulumi/pulumi-terraform-bridge/v3/pkg/tfshim/sdk-v2.(*providerWithPlanResourceChangeDispatch).Diff(0xc00051fb00, {0x16cb830, 0xc0002031d0}, {0x149dfa5, 0x12}, {0x0, 0x0}, {0x16bd900, 0xc000582050}, {0x0, ...})
  
  	/home/runner/go/pkg/mod/github.com/pulumi/pulumi-terraform-bridge/v3@v3.82.1-0.20240513144526-3242c866b548/pkg/tfshim/sdk-v2/provider2.go:688 +0xe5
  
  github.com/pulumi/pulumi-terraform-bridge/v3/pkg/tfbridge.(*Provider).Create(0xc000431980, {0x16cb830?, 0xc000202840?}, 0xc000644960)
  
  	/home/runner/go/pkg/mod/github.com/pulumi/pulumi-terraform-bridge/v3@v3.82.1-0.20240513144526-3242c866b548/pkg/tfbridge/provider.go:1096 +0x74e
  
  github.com/pulumi/pulumi/sdk/v3/proto/go._ResourceProvider_Create_Handler.func1({0x16cb830, 0xc000202840}, {0x13b1080?, 0xc000644960})
  
  	/home/runner/go/pkg/mod/github.com/pulumi/pulumi/sdk/v3@v3.115.2/proto/go/provider_grpc.pb.go:593 +0x72
  
  github.com/grpc-ecosystem/grpc-opentracing/go/otgrpc.OpenTracingServerInterceptor.func1({0x16cb830, 0xc0002020f0}, {0x13b1080, 0xc000644960}, 0xc00025fe20, 0xc00053c828)
  
  	/home/runner/go/pkg/mod/github.com/grpc-ecosystem/grpc-opentracing@v0.0.0-20180507213350-8e809c8a8645/go/otgrpc/server.go:57 +0x3d0
  
  github.com/pulumi/pulumi/sdk/v3/proto/go._ResourceProvider_Create_Handler({0x1452d60?, 0xc000431980}, {0x16cb830, 0xc0002020f0}, 0xc00046b380, 0xc0005d6d00)
  
  	/home/runner/go/pkg/mod/github.com/pulumi/pulumi/sdk/v3@v3.115.2/proto/go/provider_grpc.pb.go:5[95](https://github.com/pulumi/pulumi-fastly/actions/runs/9065253482/job/24906248746?pr=536#step:22:97) +0x135
  
  google.golang.org/grpc.(*Server).processUnaryRPC(0xc000630c00, {0x16cb830, 0xc000202060}, {0x16d5b20, 0xc00028e000}, 0xc0003ef7a0, 0xc0005c7980, 0x20ec380, 0x0)
  
  	/home/runner/go/pkg/mod/google.golang.org/grpc@v1.63.2/server.go:1369 +0xe23
  
  google.golang.org/grpc.(*Server).handleStream(0xc000630c00, {0x16d5b20, 0xc00028e000}, 0xc0003ef7a0)
  
  	/home/runner/go/pkg/mod/google.golang.org/grpc@v1.63.2/server.go:1780 +0x1016
  
  google.golang.org/grpc.(*Server).serveStreams.func2.1()
  
  	/home/runner/go/pkg/mod/google.golang.org/grpc@v1.63.2/server.go:1019 +0x8b
  
  created by google.golang.org/grpc.(*Server).serveStreams.func2 in goroutine 71
  
  	/home/runner/go/pkg/mod/google.golang.org/grpc@v1.63.2/server.go:1030 +0x135
  
  error: Preview failed: error reading from server: EOF
  error: preview failed
  Resources:
      + 1 to create
  
      command.go:118: Wrote output to /tmp/p-it-fv-az1205--service-5df87b39-19133513[97](https://github.com/pulumi/pulumi-fastly/actions/runs/9065253482/job/24906248746?pr=536#step:22:99)/command-output/pulumi-preview-initial.20240513-155556.12b44.log
      program.go:1461: Destroying stack
      command.go:46: **** Invoke '/usr/local/bin/pulumi destroy --non-interactive --yes --skip-preview' in '/tmp/p-it-fv-az1205--service-5df87b39-1913351397'
      command.go:118: Wrote output to /tmp/p-it-fv-az1205--service-5df87b39-1913351397/command-output/pulumi-destroy.20240513-155556.a60bd.log
      command.go:46: **** Invoke '/usr/local/bin/pulumi stack rm --yes' in '/tmp/p-it-fv-az1205--service-5df87b39-1913351397'
      command.go:118: Wrote output to /tmp/p-it-fv-az1205--service-5df87b39-1913351397/command-output/pulumi-stack-rm.20240513-155556.753f7.log
      program.go:852: 
          	Error Trace:	/home/runner/go/pkg/mod/github.com/pulumi/pulumi/pkg/v3@v3.[115](https://github.com/pulumi/pulumi-fastly/actions/runs/9065253482/job/24906248746?pr=536#step:22:117).2/testing/integration/program.go:852
          	            				/home/runner/work/pulumi-fastly/pulumi-fastly/examples/examples_nodejs_test.go:40
          	Error:      	Received unexpected error:
          	            	running test preview, update, and edits: initial failure: [/usr/local/bin/pulumi preview --non-interactive --diff] did not succeed after 1 tries

Output of pulumi about

.

Additional context

No response

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[VenelinMartinov]

This seems to bottom out at #1970

[t0yv0]

Yes I agree.

fastly.resourceService.validateUniqueNames expects empty set instead of null.

[t0yv0]

Can we fix this?

[mikhailshilkov]

Marked it as impact/panic. I assume it should also be a p1? Or is the panic not hittable by end users?

[VenelinMartinov]

This likely does not affect end-users right now as the bridge feature is only rolled out to a few resources.