resource/aws_route: Print more useful error message when missing valid target type

[MattMcNam]

Changes proposed in this pull request:

• Update aws_route error message to list which target types are expected when none are given

The current error message does not actually print anything after the colon since setTarget is an empty string, and while it's not too hard to figure out the actual problem, this can save a trip to the documentation.

[bflad]

Thanks @MattMcNam! 🚀

10 tests passed (all tests)
=== RUN   TestAccAWSRoute_ipv6ToPeeringConnection
--- PASS: TestAccAWSRoute_ipv6ToPeeringConnection (19.36s)
=== RUN   TestAccAWSRoute_ipv6ToInternetGateway
--- PASS: TestAccAWSRoute_ipv6ToInternetGateway (29.33s)
=== RUN   TestAccAWSRoute_ipv6Support
--- PASS: TestAccAWSRoute_ipv6Support (29.64s)
=== RUN   TestAccAWSRoute_basic
--- PASS: TestAccAWSRoute_basic (30.03s)
=== RUN   TestAccAWSRoute_doesNotCrashWithVPCEndpoint
--- PASS: TestAccAWSRoute_doesNotCrashWithVPCEndpoint (36.27s)
=== RUN   TestAccAWSRoute_changeCidr
--- PASS: TestAccAWSRoute_changeCidr (41.41s)
=== RUN   TestAccAWSRoute_changeRouteTable
--- PASS: TestAccAWSRoute_changeRouteTable (52.57s)
=== RUN   TestAccAWSRoute_ipv6ToInstance
--- PASS: TestAccAWSRoute_ipv6ToInstance (124.41s)
=== RUN   TestAccAWSRoute_ipv6ToNetworkInterface
--- PASS: TestAccAWSRoute_ipv6ToNetworkInterface (147.10s)
=== RUN   TestAccAWSRoute_noopdiff
--- PASS: TestAccAWSRoute_noopdiff (198.94s)

[bflad]

This has been released in version 1.28.0 of the AWS provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

[ghost]

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 feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!