fix: return early if no modules exist when displaying dependent modules

[Integral-Tech]

Description

When displaying dependent modules, check whether the list is empty and return early.

Motivation and Context

Currently, when no modules exist, pressing "D" or "Alt+D" to display dependent modules will crash the program.

thread 'main' panicked at src/app.rs:250:13:
index out of bounds: the len is 0 but the index is 0

How Has This Been Tested?

Tested in a QEMU virtual machine, with direct kernel boot (no initramfs).

Screenshots / Output (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (no code change)
• Refactor (refactoring production code)
• Other

Checklist:

• My code follows the code style of this project.
• I have updated the documentation and changelog accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• Rustfmt and Rust-clippy passed.

[orhun]

Thanks!