Return "Outside atlas" rather than key error

[adamltyson]

Description

What is this PR

• [x] Bug fix
• [ ] Addition of a new feature
• [ ] Other

Why is this PR needed? When querying for structures as ID from coordinates, out of bounds coordinates return 0, but when asking for an acronym, it raises a KeyError value.

What does this PR do? Rather than a key error, "Outside atlas" is returned

References

Closes #157

How has this PR been tested?

New tests added & checked manually

Is this a breaking change?

Nope

Does this PR require an update to the documentation?

Don't think so

Checklist:

• [x] The code has been tested locally
• [x] Tests have been added to cover all new functionality (unit & integration)
• [ ] The documentation has been updated to reflect any changes
• [x] The code has been formatted with pre-commit