Add image for clients with missing or unknown platform

[stintel]

When running the UI in dev mode, having a client with missing or unknown platform causes an error. Add a fallback image to fix this.

[ciaranj]

Initially this looked out to me, although src={ClientImages[client.platform] ?? UnknownImage} and alt={client.platform || "Unknown device"} are subtly different. An invalid (from the perspective of the ClientImages constant) client.platform value will return the 'UnknownImage' image, but display the value of the client.platform variable. Only an undefined/null client.platform will display the 'Unknown Device' label. Was this your intent @stintel ?

edit: Which on further analysis checked the type of client.platform, looks non-nullable, so I don't think it's ever possible for 'unknown Device' to be shown.

[stintel]

My intent was to fix the error. Probably didn't think hard enough about the implication of the alt change. Have any suggestions to make/keep things consistent?

[ciaranj]

My intent was to fix the error. Probably didn't think hard enough about the implication of the alt change. Have any suggestions to make/keep things consistent?

I guess something like: ClientImages[client.platform] ? client.platform : "Unknown device" would give you a consistent logic.