Rails 7 deprecates Enumerable#sum and Array#sum

Rails 7 deprecates Enumerable#sum to the calls with non-numeric arguments. To ignore the warning we should use a suitable initial argument.

Before Rails 7

1=> %w[foo bar].sum
2=> "foobar"
3
4=> [[1, 2], [3, 4, 5]].sum
5=> [1, 2, 3, 4, 5]
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After Rails 7

1=> %w[foo bar].sum
2=> Rails 7.0 has deprecated Enumerable.sum in favor of Ruby's native implementation available since 2.4.
3   Sum of non-numeric elements requires an initial argument.
4
5=> [[1, 2], [3, 4, 5]].sum
6=> Rails 7.0 has deprecated Enumerable.sum in favor of Ruby's native implementation available since 2.4.
7   Sum of non-numeric elements requires an initial argument.
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To avoid the deprecation warning, we should use suitable argument as below.

1=> %w[foo bar].sum('')
2=> "foobar"
3
4=> [[1, 2], [3, 4, 5]].sum([])
5=> [1, 2, 3, 4, 5]
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Check out this pull request for more details.