Null checks in TypeService

[dmitrii-ubskii]

Usage and product changes

We expand null checking in transaction TypeService, which is used for handling Concept API type requests. This replaces the uninformative NPE with a Missing Concept error message.

[vaticle-bot]

PR Review Checklist

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Trivial Change

• [x] This change is trivial and does not require a code or architecture review.

Code

• [ ] Packages, classes, and methods have a single domain of responsibility.
• [ ] Packages, classes, and methods are grouped into cohesive and consistent domain model.
• [ ] The code is canonical and the minimum required to achieve the goal.
• [ ] Modules, libraries, and APIs are easy to use, robust (foolproof and not errorprone), and tested.
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Architecture

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• [ ] Any required build and release automations are updated and/or implemented.
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• [ ] The architecture is extensible and scalable.