put Environments in try-catch block

[ClemensBuechner]

do error handling in search, so we don't need to do it in every environment

[FlorianPommerening]

This is already done (the try-catch is there at least) and we have #72 for general refactoring of error handling. I'll close this and mention that we want to move some of the logic from the environment to the search in #72. Feel free to reopen if this was about something else.