Description

Trie expects non-empty list, but gets empty coverage. It is unclear how exactly empty coverage is generated but this commit adds check for such cases.

Fixes #655, #658

Type of Change

• Minor bug fix (non-breaking small changes)
• Refactoring (typos and non-functional changes)

How Has This Been Tested?

Automated Testing

All tests should pass

Checklist:

• The change followed the style guidelines of the UTBot project
• Self-review of the code is passed
• The change contains enough commentaries, particularly in hard-to-understand areas
• New documentation is provided or existed one is altered
• No new warnings
• New tests have been added
• All tests pass locally with my changes