dApp - add paramter validation to connection methods and more detailed error messages

[weilbith]

Description

At the moment, the user does not get early feedback when he inserts (wrong) connection options. Even worse, when the connection fails, there is only a single generic error message.
To improve the user experience, there should be options to very input parameters like for transfers. With that given, it might not even be necessary to provide more detailed error messages if a connection fails. Though some standard scenarios should be better recognized as for example when the user denies a connection in MetaMask or WalletConnect.

Acceptance criteria

Tasks

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