command/jsonplan: fix panic when filteredAfter is null (#20096)

* command/jsonplan: fix panic when filteredAfter is null
* command/jsonconfig: provider short name is required to properly look up resource schema

command/jsonconfig/config.go

@@ -224,8 +224,15 @@ func marshalResources(resources map[string]*configs.Resource, schemas *terraform
 			}
 		}
 
-		schema, schemaVersion := schemas.ResourceTypeConfig(v.ProviderConfigAddr().String(), v.Mode, v.Type)
-		r.SchemaVersion = schemaVersion
+		schema, schemaVer := schemas.ResourceTypeConfig(
+			v.ProviderConfigAddr().StringCompact(),
+			v.Mode,
+			v.Type,
+		)
+		if schema == nil {
+			return nil, fmt.Errorf("no schema found for %s", v.Addr().String())
+		}
+		r.SchemaVersion = schemaVer
 
 		r.Expressions = marshalExpressions(v.Config, schema)
 

command/jsonconfig/expression_test.go

@@ -0,0 +1,73 @@
+package jsonconfig
+
+import (
+	"encoding/json"
+	"reflect"
+	"testing"
+
+	"github.com/zclconf/go-cty/cty"
+
+	"github.com/hashicorp/hcl2/hcl"
+	"github.com/hashicorp/hcl2/hcl/hclsyntax"
+	"github.com/hashicorp/terraform/configs/configschema"
+)
+
+func TestMarshalExpressions(t *testing.T) {
+	tests := []struct {
+		Input  hcl.Body
+		Schema *configschema.Block
+		Want   expressions
+	}{
+		{
+			&hclsyntax.Body{
+				Attributes: hclsyntax.Attributes{
+					"foo": &hclsyntax.Attribute{
+						Expr: &hclsyntax.LiteralValueExpr{
+							Val: cty.StringVal("bar"),
+						},
+					},
+				},
+			},
+			&configschema.Block{
+				Attributes: map[string]*configschema.Attribute{
+					"foo": {
+						Type:     cty.String,
+						Optional: true,
+					},
+				},
+			},
+			expressions{
+				"foo": expression{
+					ConstantValue: json.RawMessage([]byte(`"bar"`)),
+					References:    []string(nil),
+				},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		got := marshalExpressions(test.Input, test.Schema)
+		if !reflect.DeepEqual(got, test.Want) {
+			t.Fatalf("wrong result:\nGot: %#v\nWant: %#v\n", got, test.Want)
+		}
+	}
+}
+
+func TestMarshalExpression(t *testing.T) {
+	tests := []struct {
+		Input hcl.Expression
+		Want  expression
+	}{
+		{
+			nil,
+			expression{},
+		},
+	}
+
+	for _, test := range tests {
+		got := marshalExpression(test.Input)
+		if !reflect.DeepEqual(got, test.Want) {
+			t.Fatalf("wrong result:\nGot: %#v\nWant: %#v\n", got, test.Want)
+		}
+	}
+}

command/jsonplan/plan.go

@@ -176,9 +176,13 @@ func (p *plan) marshalResourceChanges(changes *plans.Changes, schemas *terraform
 				})
 			} else {
 				filteredAfter := omitUnknowns(changeV.After)
-				after, err = ctyjson.Marshal(filteredAfter, filteredAfter.Type())
-				if err != nil {
-					return err
+				if filteredAfter.IsNull() {
+					after = nil
+				} else {
+					after, err = ctyjson.Marshal(filteredAfter, filteredAfter.Type())
+					if err != nil {
+						return err
+					}
 				}
 				afterUnknown = unknownAsBool(changeV.After)
 			}