fix(tesseract): Don't generate COALESCE with single argument

[waralexrom]

Check List

• Tests have been run in packages where changes made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Issue Reference this PR resolves

[For example #12]

Description of Changes Made (if issue reference is not provided)

[Description goes here]

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.81%. Comparing base (0e95f18) to head (f180225).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #9300   +/-   ##
=======================================
  Coverage   83.81%   83.81%           
=======================================
  Files         229      229           
  Lines       82658    82658           
=======================================
  Hits        69283    69283           
  Misses      13375    13375           

Flag	Coverage Δ
cubesql	83.81% <ø> (ø)

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[KSDaemon]

👍🏻 LGTM!