fix switch chain

[lionellbriones]

Motivation and Context

Jira Link: https://toruslabs.atlassian.net/browse/PD-3882

Description

Save current chain on demo app to persist chain on reload
Catch error on Adding + Switch chain flow

How has this been tested?

Tested demo app by switching chain and refreshing page to see if the same chain is loaded on window reload.

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.

[arch1995]

lgtm