#56 implementing exception handling for requests to the flightscontroller

[jobdk]

This pr is created to get some feedback on the exception handling. With the changes I check that the software does not shut down when:

• the connection does not exist
• an attribute is missing for British airways

If you want to test the changes using the test software and don't know how it works hit me up. To test use the testsoftware branch "fix_apis"

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