Support case where issue reporter is blank for new issue creation event

[mickmister]

An issue is occurring when no Reporter field is present on a newly created issue. According to the customer, the reporter field is hidden in the field setting scheme in JIRA. The issue is happening here:

mattermost-plugin-jira/server/issue_parser.go

Line 28 in d08f7f7

avatarLink := fmt.Sprintf("", issue.Fields.Reporter.AvatarUrls.One6X16)

We'll also want to make sure we are defensive with other instances of the Reporter field, as possibly look into other potential cases of missing fields in the codebase.

Issue created from a Mattermost message by @hanzei.

[raghavaggarwal2308]

@hanzei @mickmister Just for clarification:

• On what action the issue is being caused? Is the user trying to create an issue using the MM interface?

[hanzei]

@raghavaggarwal2308 Yes, the bug happens when a user creates an issue via the MM UI.