Handle `user` being undefined at a global level.

[ultraviolet10]

For components in the iframe that need the logged-in user's details, we always need to check whether user is defined or not:

if (!user) {
  // handle it in some manner
}

Ideally we want to define a global invariant which ensures user is defined or no dependent component is mounted until so.

[linear]

HAPPY-239 Handle `user` being undefined at a global level.

For components in the iframe that need the logged-in user's details, we always need to check whether user is defined or not:

if (!user) {
  // handle it in some manner
}

Ideally we want to define a global invariant which ensures user is defined or no dependent component is mounted until so.

[ultraviolet10]

cf: https://github.com/HappyChainDevs/happychain/pull/231/files#r1835088996