When the node explorer cannot connect to the specified node it retries every five seconds indefinitely. The UI becomes unresponsive. This is OK when the node it's trying to connect to is simply not available yet. If the connection cannot be established because the wrong port or credentials were entered, this behaviour is not desirable. The user is given no feedback (except the log output from the gradle task) and ultimately has to force close the UI.
How to reproduce:
Start the node explorer with `./gradlew tools:explorer:run`. Enter incorrect node/ login data (for instance specify a port on which no node is running).
Do not retry to establish the connection automatically, at least not indefinitely. Inform the user in the UI that the connection could not be establish and let them retry manually.