Allow empty coverage

[mosuem]

Fix a bug where empty coverage leads to workflow failure.

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[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:firehose	0.3.21	ready to publish	firehose-v0.3.21
package:dart_flutter_team_lints	1.0.0	already published at pub.dev

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.

[github-actions]

PR Health

Package publish validation ✔️

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Package	Version	Status
package:firehose	0.3.21	ready to publish
package:dart_flutter_team_lints	1.0.0	already published at pub.dev

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.

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// Copyright (c) 2023, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

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Changelog Entry ✔️

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