fix(amazonq): Add error handling of agentic chat

[leigaol]

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Description

Fix of https://github.com/aws/aws-toolkit-jetbrains/pull/5571/files#diff-cd56bad1ef35b0dcfb5c729a7b22594c1b15f8fa64d7be9743bb125c5e4f7c1dR99

I manually added exception in showResult

if (messageToChat.contains("abc")) {
                    throw Exception("abc err")
                }

Checklist

• My code follows the code style of this project
• I have added tests to cover my changes
• A short description of the change has been added to the CHANGELOG if the change is customer-facing in the IDE.
• I have added metrics for my changes (if required)

License

I confirm that my contribution is made under the terms of the Apache 2.0 license.