Fix: fail when optimiser returns no feasible solution

[Her0n24]

Related Issue / Discussion:

This PR addresses https://github.com/52North/WeatherRoutingTool/issues/164
Relates to #29 (closed)
Fixes Issue #164

Changes:

Please list the central functionalities that have been changed:

• Modified: Guard Genetic.terminate() against empty/ None optimisation results and raise a descriptive error that is causing the crash
• New: test_genetic_termination.py is a regression test that asserts Genetic.terminate() fails fast with a clear RuntimeError when the result is empty

Summary:

Under certain condition/ constraints (e.g. water_depth), the genetic optimiser can end up with no feasible solution. In that case, the result res.F/ res.X are empty or None.

Behavior before
Genetic.terminate() unconditionally called res.F.argmin(), which could crash with AttributeError as res.F/ res.X were None. This hides the real cause of the error.

Behavior after
Genetic.terminate() detects None in res.F/ res.X and raises a clear RuntimeError explaining no feasible route found and suggesting to relax constraints.

Dependencies:

No new runtime dependencies.

PR Checklist:

In the context of this PR, I:

• have (already previously) filled the 52North Contributor License Agreement and received positive feedback on this matter
• have filled the 52North Contributor License Agreement and am waiting for feedback
• provide unit tests embedded in the WRT test framework (WeatherRoutingTool/tests) that allow the simple testing of the new/modified functionalities. All (previous and new) unit tests execute without new error messages.
• ensure that the code formatter runs without errors/warnings
• ensure that my changes follow the WRT’s guidelines for contributing at the time of the contribution