Decimal.TryParse(subKey, out decimalVersion) is incorrect it SqlServerDetector.TryGetLocalDBVersionInstalled method.
CultureInfo parameter should be specified. for example:
Decimal.TryParse(subKey, NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out decimalVersion)

C:!entityframework\efxx\EF.xunit.targets(14,9): error : EntityFramework.PowerShell.UnitTests.ConnectionFactoryConfigTests.SqlServerDetector_ignores_LocalDB_versions_that_are_not_numeric_when_multiple_versions_are_installed: Assert.Equal() Failure
C:!entityframework\efxx\EF.xunit.targets(14,9): error : Expected: 12.0
C:!entityframework\efxx\EF.xunit.targets(14,9): error : Actual: (null)