Why this line is not covered? Xcode code coverage

Question

I'm experiencing an issue with the report of code coverage in Xcode. As you can see from this screenshot:

On the left tab, line 58 is "touched" from the break-point, and on the right tab, the test passes. While on the right tab, I'm running only the test on line 37.

Why does Xcode sign the line 58 in red, as not covered?

Line 53 is not "touched" (if I set a break-point there). Using SQLite as a database.

The entire project is available here.

EDIT: Adding code:

Test.swift

func testAddFuelFail() {
  fuelsManager.dropTable()
  XCTAssertEqual(addFuel(), -1)
}

FuelsManager.swift

func addFuel(dateOfFuel: Date, mileageOnSave: Int, quantityOfFuel: Double, pricePerUnitOfFuel: Double) -> Int64 {
  let insertFuel = fuelsTable.insert(date <- dateOfFuel, mileage <- mileageOnSave, quantity <- quantityOfFuel, pricePerUnit <- pricePerUnitOfFuel)
  do {
    let id = try database!.run(insertFuel)
      return id
  } catch {
    print(error)
  }
  return -1
}

Answer 1

Actually its a bug reported here.

1. Coverage number varies between multiple runs on XC 10 on the same binary. Like in first run it shows x% vs in another run it will show y% keeping the same code.
2. Coverage number/Number of tests varies while running on 11.4 simulator and 12.0 simulator, both ran on XC 10
3. Number of tests also a little different like in some run it was 5507 tests vs in some runs it was 5506.

XC 10 certainly came with lots of bugs.