Make message in LockError optional to support backwards compatibility

[dvora-h]

Pull Request check-list

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• Do tests and lints pass with this change?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?
• Was the change added to CHANGES file?

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Description of change

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.86%. Comparing base (2f88840) to head (75a7bf3).
Report is 12 commits behind head on master.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3176      +/-   ##
==========================================
+ Coverage   91.84%   91.86%   +0.01%     
==========================================
  Files         128      128              
  Lines       33232    33322      +90     
==========================================
+ Hits        30523    30612      +89     
- Misses       2709     2710       +1     

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