[rush] Fixed the issue where the lockfile object has an nullish value causing yaml.dump to report an error

[fzxen]

Summary

Fixes #5053

After I set the preventManualShrinkwrapChanges field in the pnpm-config.json file to true, I successfully reproduced this problem.

Details

The following code logic will result in the lockfile object having nullish value, so the yamlModule.safeDump method will throw an exception.

rushstack/libraries/rush-lib/src/logic/pnpm/PnpmShrinkWrapFileConverters.ts

Lines 51 to 64 in 724aa51

	const dependencies: ResolvedDependencies | undefined =
	from.dependencies == null ? from.dependencies : moveSpecifiers(from.dependencies);
	const devDependencies: ResolvedDependencies | undefined =
	from.devDependencies == null ? from.devDependencies : moveSpecifiers(from.devDependencies);
	const optionalDependencies: ResolvedDependencies | undefined =
	from.optionalDependencies == null ? from.optionalDependencies : moveSpecifiers(from.optionalDependencies);
	return {
	...from,
	specifiers,
	dependencies,
	devDependencies,
	optionalDependencies
	};

How it was tested

I have added some unit tests to ensure that the importers field in the lockfile will not contain nullish values.

[octogonz]

@fzxen thanks for making this fix! It's been published with Rush 5.147.2 🚀