Swift better error handling

[grvgoel81]

Motivation and Context

Swift better error handling

Jira Link:

Description

• Swift better error handling.
• Previously there is generic error everytime "privateKeyNot Generated Error" but after update it gives exact error like "retrieve or import share failed" in screenshot.

How has this been tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project. (run lint)
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My code requires a db migration.

[metalurgical]

This is much better thanks.

Please also remove this function as well:

public func throwKeyNotGeneratedError() -> FlutterError

[grvgoel81]

This is much better thanks.

Please also remove this function as well:

public func throwKeyNotGeneratedError() -> FlutterError

done.

[chaitanyapotti]

lgtm