"panic: value is not an object" when MapNestedAttributes contains more than one computed attribute

[avinashbot]

When working with the terraform plugin framework, defining an attribute with MapNestedAttributes that contains more than one computed attribute crashes terraform before a plan/apply. I couldn't find any mention of the panic message (panic: value is not an object) anywhere in the issues before. The stacktrace points here in go-cty.

I saw this happening in my provider, but I can also reproduce it with the hashicups starter template. I've attached the relevant minimal reproduction code below.

Terraform Version

Terraform v1.0.5
on linux_amd64

Terraform Configuration Files

Implementation:

func (r resourceOrderType) GetSchema(_ context.Context) (schema.Schema, []*tfprotov6.Diagnostic) {
	return schema.Schema{
		Attributes: map[string]schema.Attribute{
			"items": {
				Required: true,
				Attributes: schema.MapNestedAttributes(
					map[string]schema.Attribute{
						"id": {
							Type:     types.NumberType,
							Optional: true,
						},
						"name": {
							Type:     types.StringType,
							Optional: true,
							Computed: true, // <- first computed
						},
						"description": {
							Type:     types.StringType,
							Optional: true,
							Computed: true, // <- second computed
						},
					},
					schema.MapNestedAttributesOptions{},
				),
			},
		},
	}, nil
}

Config:

The crash happens when the "items" are present in the config, but the actual content doesn't matter.

resource "hashicups_order" "edu" {
  items = {
    "one" : {
      id = 1
    }
    "two" : {
      id = 2
    }
  }
}

Debug Output

2021-08-29T01:26:37.501-0700 [DEBUG] refresh: hashicups_order.edu: no state, so not refreshing
2021-08-29T01:26:37.501-0700 [TRACE] NodeAbstractResouceInstance.writeResourceInstanceState to refreshState for hashicups_order.edu
2021-08-29T01:26:37.501-0700 [TRACE] NodeAbstractResouceInstance.writeResourceInstanceState: removing state object for hashicups_order.edu
2021-08-29T01:26:37.501-0700 [TRACE] Re-validating config for "hashicups_order.edu"
2021-08-29T01:26:37.501-0700 [TRACE] GRPCProvider.v6: ValidateResourceConfig
2021-08-29T01:26:37.501-0700 [TRACE] GRPCProvider.v6: PlanResourceChange
2021-08-29T01:26:37.502-0700 [TRACE] vertex "hashicups_order.edu": visit complete
panic: value is not an object

goroutine 79 [running]:
github.com/zclconf/go-cty/cty.Value.GetAttr(0x2b44678, 0xc000122369, 0x2269840, 0xc000be2f90, 0xc0007822a0, 0xb, 0x8d851d, 0x2b44720, 0xc00058dab0, 0x2b44720)
	/home/circleci/go/pkg/mod/github.com/zclconf/go-cty@v1.9.1/cty/value_ops.go:744 +0x44e
github.com/hashicorp/terraform/internal/plans/objchange.assertPlannedAttrValid(0xc0007822a0, 0xb, 0xc0004addc0, 0x2b44720, 0xc000be3150, 0x0, 0x0, 0x2b44678, 0xc000122369, 0x2269840, ...)
	/home/circleci/project/project/internal/plans/objchange/plan_valid.go:248 +0x85
github.com/hashicorp/terraform/internal/plans/objchange.assertPlannedAttrsValid(0xc000517530, 0x2b44720, 0xc000be3150, 0x0, 0x0, 0x2b44678, 0xc000122369, 0x2269840, 0xc000be2570, 0x2b44678, ...)
	/home/circleci/project/project/internal/plans/objchange/plan_valid.go:241 +0x214
github.com/hashicorp/terraform/internal/plans/objchange.assertPlannedObjectValid(0xc00094e580, 0x2b44720, 0xc000be3110, 0x0, 0x0, 0x2b44758, 0xc000b3ca40, 0x233e560, 0xc000328b40, 0x2b44758, ...)
	/home/circleci/project/project/internal/plans/objchange/plan_valid.go:394 +0x7db
github.com/hashicorp/terraform/internal/plans/objchange.assertPlannedObjectValid(0xc00094e580, 0x0, 0x0, 0x0, 0x0, 0x2b44720, 0xc000b3caa0, 0x233e560, 0xc000328c00, 0x2b44720, ...)
	/home/circleci/project/project/internal/plans/objchange/plan_valid.go:427 +0x154e
github.com/hashicorp/terraform/internal/plans/objchange.assertPlannedValueValid(0xc0004add80, 0x0, 0x0, 0x0, 0x0, 0x2b44720, 0xc000b3caa0, 0x233e560, 0xc000328c00, 0x2b44720, ...)
	/home/circleci/project/project/internal/plans/objchange/plan_valid.go:293 +0x986
github.com/hashicorp/terraform/internal/plans/objchange.assertPlannedAttrValid(0xc000782248, 0x5, 0xc0004add80, 0x2b44758, 0xc000be2830, 0x0, 0x0, 0x2b44758, 0xc000b3cab0, 0x233e560, ...)
	/home/circleci/project/project/internal/plans/objchange/plan_valid.go:256 +0x332
github.com/hashicorp/terraform/internal/plans/objchange.assertPlannedAttrsValid(0xc000516bd0, 0x2b44758, 0xc000be2830, 0x0, 0x0, 0x2b44758, 0xc000b3cab0, 0x233e560, 0xc000328c30, 0x2b44758, ...)
	/home/circleci/project/project/internal/plans/objchange/plan_valid.go:241 +0x214
github.com/hashicorp/terraform/internal/plans/objchange.assertPlanValid(0xc000517500, 0x2b44758, 0xc000be2830, 0x0, 0x0, 0x2b44758, 0xc000b3cab0, 0x233e560, 0xc000328c30, 0x2b44758, ...)
	/home/circleci/project/project/internal/plans/objchange/plan_valid.go:57 +0x41c
github.com/hashicorp/terraform/internal/plans/objchange.AssertPlanValid(...)
	/home/circleci/project/project/internal/plans/objchange/plan_valid.go:36
github.com/hashicorp/terraform/internal/terraform.(*NodeAbstractResourceInstance).plan(0xc0005d0a80, 0x2b74d00, 0xc0006fe8c0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/home/circleci/project/project/internal/terraform/node_resource_abstract_instance.go:783 +0x17e5
github.com/hashicorp/terraform/internal/terraform.(*NodePlannableResourceInstance).managedResourceExecute(0xc0007ad740, 0x2b74d00, 0xc0006fe8c0, 0x40ac08, 0x269fd80, 0xc00099dc50)
	/home/circleci/project/project/internal/terraform/node_resource_plan_instance.go:196 +0x8cb
github.com/hashicorp/terraform/internal/terraform.(*NodePlannableResourceInstance).Execute(0xc0007ad740, 0x2b74d00, 0xc0006fe8c0, 0x7faeb1660302, 0xc00099dce8, 0x40bb05, 0x2387b80)
	/home/circleci/project/project/internal/terraform/node_resource_plan_instance.go:54 +0xb3
github.com/hashicorp/terraform/internal/terraform.(*ContextGraphWalker).Execute(0xc0001a7040, 0x2b74d00, 0xc0006fe8c0, 0x7faeb16603d8, 0xc0007ad740, 0x0, 0x0, 0x0)
	/home/circleci/project/project/internal/terraform/graph_walk_context.go:129 +0xbf
github.com/hashicorp/terraform/internal/terraform.(*Graph).walk.func1(0x269fd80, 0xc0007ad740, 0x0, 0x0, 0x0)
	/home/circleci/project/project/internal/terraform/graph.go:59 +0xbd3
github.com/hashicorp/terraform/internal/dag.(*Walker).walkVertex(0xc000091200, 0x269fd80, 0xc0007ad740, 0xc0007bcc80)
	/home/circleci/project/project/internal/dag/walk.go:381 +0x288
created by github.com/hashicorp/terraform/internal/dag.(*Walker).Update
	/home/circleci/project/project/internal/dag/walk.go:304 +0x1246

!!!!!!!!!!!!!!!!!!!!!!!!!!! TERRAFORM CRASH !!!!!!!!!!!!!!!!!!!!!!!!!!!!

Crash Output

https://gist.github.com/avinashbot/b1ce31f9cfb0501b8f349135a6bb9bda

Expected Behavior

Terraform doesn't crash on me.

Actual Behavior

Terraform crashed on me.

Steps to Reproduce

1. terraform init
2. terraform plan

Additional Context

References

[github-actions]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.