Fix index check for list in utilities.py

[knap1930]

moto throws a IndexError: list index out of range when specifying a list index in ProjectionExpression that matches the length of the list, so if you try select [0] for an empty list, or [1] for a list with 1 element in it.

data = []
len(data) == 0
data[0] -> IndexError: list index out of range

[bpandola]

Let's add a test case (fails before your change, succeeds after) that covers this scenario. Thanks.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.12%. Comparing base (c7b3d3c) to head (6f9bab8).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #9728   +/-   ##
=======================================
  Coverage   93.12%   93.12%           
=======================================
  Files        1308     1308           
  Lines      118884   118884           
=======================================
+ Hits       110706   110707    +1     
+ Misses       8178     8177    -1     

Flag	Coverage Δ
servertests	28.89% <ø> (ø)
unittests	93.09% <ø> (+<0.01%)	⬆️

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