AdminHandler's DescribeWorkflowExecution endpoint panics when using grpc transport

[Shaddoll]

Description

AdminHandler's DescribeWorkflowExecution endpoint panics when using grpc transport.

Steps to Reproduce / How to Trigger

Use Cadence CLI to describe a workflow that doesn't exist.
e.g. cadence --do cadence-system adm wf desc --wid aaaa

Expected Behavior

The CLI should print EntityNotExistsError

Actual Behavior

The CLI prints a message including "panics: strconv.Atoi ..."

Logs / Screenshots

Error: Get workflow mutableState failed: code:unknown message:panic: strconv.Atoi: parsing "": invalid syntax

Environment

• Cadence server version: latest version (master branch)
• Cadence SDK language and version (if applicable): N/A
• Cadence web version (if applicable): N/A
• DB & version: Cassandra
• Scale: N/A

[Shaddoll]

The reason is that the handler returns a non-nil response on this error branch. And inside this proto mapper, we convert a string to an integer.

The fix should be returning nil, err at that line. We should also consider changing the type of this field to int32.

[Kavish022]

@Shaddoll If the issue still persists and active then I would like to take this please.

[Shaddoll]

@Kavish022 Thank you. Feel free to take it.