Don't skip the type in a composite literal

[bobg]

Fixes #26. Many thanks to @mattkasun for the bug report!

[github-actions]

Modver result

This report was generated by Modver,
a Go package and command that helps you obey semantic versioning rules in your Go module.

This PR does not require a change in your module’s version number.
(You might still consider bumping the patchlevel anyway.)

[coveralls]

Pull Request Test Coverage Report for Build 20149744771

Details

• 1 of 3 (33.33%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.3%) to 68.409%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
expr.go	1	3	33.33%

Totals
Change from base Build 19779387699:	0.3%
Covered Lines:	864
Relevant Lines:	1263

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💛 - Coveralls