io: add missing checks

[jarevalo-ledger]

Description

Fix os_io_rx_evt fuzzing

Changes include

• Bugfix (non-breaking change that solves an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)
• Tests
• Documentation
• Other (for changes that might not fit in any category)

Breaking changes

Please complete this section if any breaking changes have been made, otherwise delete it.

Additional comments

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Auto cherry-pick in API_LEVEL

If requested to port the commits from this PR on a dedicated API_LEVEL branch,
select the targeted one(s), or add new references if not listed:

[x] TARGET_API_LEVEL: API_LEVEL_25

This will only create the PR with cherry-picks, ready to be reviewed and merged.

Remember:

• The merge will ALWAYS be a manual operation.
• It is possible the cherry-picks don't apply correctly, mainly if previous commits have been forgotten.
• In case of failure, there is no other solution than redo the operation manually...

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.73%. Comparing base (799521c) to head (881f27c).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1364   +/-   ##
=======================================
  Coverage   79.73%   79.73%           
=======================================
  Files          43       43           
  Lines        4969     4969           
  Branches      733      733           
=======================================
  Hits         3962     3962           
  Misses        919      919           
  Partials       88       88           

Flag	Coverage Δ
unittests	79.73% <ø> (ø)

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