r/aws_security_group_rule: Prevent crash when empty strings in prefix_list_ids

[ewbankkit]

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Closes #26191.

Before fix:

% make testacc TESTARGS='-run=TestAccVPCSecurityGroupRule_prefixListEmptyString' PKG=ec2
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./internal/service/ec2/... -v -count 1 -parallel 20  -run=TestAccVPCSecurityGroupRule_prefixListEmptyString -timeout 180m
=== RUN   TestAccVPCSecurityGroupRule_prefixListEmptyString
=== PAUSE TestAccVPCSecurityGroupRule_prefixListEmptyString
=== CONT  TestAccVPCSecurityGroupRule_prefixListEmptyString
panic: interface conversion: interface {} is nil, not string

goroutine 1917 [running]:
github.com/hashicorp/terraform-provider-aws/internal/service/ec2.expandIpPermission(0x0?, 0xc0064bbe30)
	/Users/ewbankkit/altsrc.2/github.com/terraform-providers/terraform-provider-aws/internal/service/ec2/vpc_security_group_rule.go:718 +0xf25
github.com/hashicorp/terraform-provider-aws/internal/service/ec2.resourceSecurityGroupRuleCreate(0x0?, {0x98c5bc0?, 0xc004ac0a80?})
	/Users/ewbankkit/altsrc.2/github.com/terraform-providers/terraform-provider-aws/internal/service/ec2/vpc_security_group_rule.go:155 +0x227
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).create(0xbce7060?, {0xbce7060?, 0xc0022d4090?}, 0xd?, {0x98c5bc0?, 0xc004ac0a80?})
	/Users/ewbankkit/go/pkg/mod/github.com/hashicorp/terraform-plugin-sdk/v2@v2.20.0/helper/schema/resource.go:695 +0x178
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).Apply(0xc0032bfce0, {0xbce7060, 0xc0022d4090}, 0xc0015ef5f0, 0xc0055e8d00, {0x98c5bc0, 0xc004ac0a80})
	/Users/ewbankkit/go/pkg/mod/github.com/hashicorp/terraform-plugin-sdk/v2@v2.20.0/helper/schema/resource.go:837 +0xa7a
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*GRPCProviderServer).ApplyResourceChange(0xc0030cab58, {0xbce7060?, 0xc0022d1fb0?}, 0xc0005c9310)
	/Users/ewbankkit/go/pkg/mod/github.com/hashicorp/terraform-plugin-sdk/v2@v2.20.0/helper/schema/grpc_provider.go:1021 +0xe3c
github.com/hashicorp/terraform-plugin-mux/tf5muxserver.muxServer.ApplyResourceChange({0xc0027d4ea0, 0xc0027d4f00, {0xc0005c5900, 0x2, 0x2}, 0xc0027d4ed0, 0xc00309f3c0, 0xc005a8fc50, 0xc0027d4f30}, {0xbce7060, ...}, ...)
	/Users/ewbankkit/go/pkg/mod/github.com/hashicorp/terraform-plugin-mux@v0.7.0/tf5muxserver/mux_server_ApplyResourceChange.go:27 +0x142
github.com/hashicorp/terraform-plugin-go/tfprotov5/tf5server.(*server).ApplyResourceChange(0xc002ed2460, {0xbce7060?, 0xc0022c59b0?}, 0xc000b19960)
	/Users/ewbankkit/go/pkg/mod/github.com/hashicorp/terraform-plugin-go@v0.13.0/tfprotov5/tf5server/server.go:813 +0x4fc
github.com/hashicorp/terraform-plugin-go/tfprotov5/internal/tfplugin5._Provider_ApplyResourceChange_Handler({0xab5f2c0?, 0xc002ed2460}, {0xbce7060, 0xc0022c59b0}, 0xc000b19810, 0x0)
	/Users/ewbankkit/go/pkg/mod/github.com/hashicorp/terraform-plugin-go@v0.13.0/tfprotov5/internal/tfplugin5/tfplugin5_grpc.pb.go:385 +0x170
google.golang.org/grpc.(*Server).processUnaryRPC(0xc0000005a0, {0xbcec808, 0xc00624a680}, 0xc0021818c0, 0xc00223ef60, 0x115062e0, 0x0)
	/Users/ewbankkit/go/pkg/mod/google.golang.org/grpc@v1.48.0/server.go:1295 +0xb0b
google.golang.org/grpc.(*Server).handleStream(0xc0000005a0, {0xbcec808, 0xc00624a680}, 0xc0021818c0, 0x0)
	/Users/ewbankkit/go/pkg/mod/google.golang.org/grpc@v1.48.0/server.go:1636 +0xa1b
google.golang.org/grpc.(*Server).serveStreams.func1.2()
	/Users/ewbankkit/go/pkg/mod/google.golang.org/grpc@v1.48.0/server.go:932 +0x98
created by google.golang.org/grpc.(*Server).serveStreams.func1
	/Users/ewbankkit/go/pkg/mod/google.golang.org/grpc@v1.48.0/server.go:930 +0x28a
FAIL	github.com/hashicorp/terraform-provider-aws/internal/service/ec2	13.934s
FAIL
make: *** [testacc] Error 1

Now:

% make testacc TESTARGS='-run=TestAccVPCSecurityGroupRule_prefixList' PKG=ec2 ACCTEST_PARALLELISM=2
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./internal/service/ec2/... -v -count 1 -parallel 2  -run=TestAccVPCSecurityGroupRule_prefixList -timeout 180m
=== RUN   TestAccVPCSecurityGroupRule_prefixListEgress
=== PAUSE TestAccVPCSecurityGroupRule_prefixListEgress
=== RUN   TestAccVPCSecurityGroupRule_prefixListEmptyString
=== PAUSE TestAccVPCSecurityGroupRule_prefixListEmptyString
=== CONT  TestAccVPCSecurityGroupRule_prefixListEgress
=== CONT  TestAccVPCSecurityGroupRule_prefixListEmptyString
--- PASS: TestAccVPCSecurityGroupRule_prefixListEmptyString (1.76s)
--- PASS: TestAccVPCSecurityGroupRule_prefixListEgress (34.89s)
PASS
ok  	github.com/hashicorp/terraform-provider-aws/internal/service/ec2	39.095s

[github-actions]

This functionality has been released in v4.26.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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