Resource file exists in swift package manager vs app

AppContentView.swift

import SwiftUI

import spmlib


struct ContentView: View {
    let l = SPMLib()
    
    var body: some View {
        VStack {
            Text("SPMLib version: \(l.version())")
            Text("spm data.json exists: \(String(describing: l.fileExists(name: "data", type: "json")))")
            Text("spm appdata.json exists: \(String(describing: l.fileExists(name: "appdata", type: "json")))")
            Text("app data.json exists: \(String(describing: l.fileExistsInApp(name: "data", type: "json")))")
            Text("app appdata.json exists: \(String(describing: l.fileExistsInApp(name: "appdata", type: "json")))")
        }
        .padding()
    }
}

package.swift

// swift-tools-version: 5.9
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "spmlib",
    products: [
        // Products define the executables and libraries a package produces, making them visible to other packages.
        .library(
            name: "spmlib",
            targets: ["spmlib"]
        ),
    ],
    targets: [
        // Targets are the basic building blocks of a package, defining a module or a test suite.
        // Targets can depend on other targets in this package and products from dependencies.
        .target(
            name: "spmlib",
            resources: [.copy("data.json")]),
        .testTarget(
            name: "spmlibTests",
            dependencies: ["spmlib"]),
    ]
)

spmlib.swift

import Foundation

public struct SPMLib {
    public init() {}

    public func version() -> String {
        return "v1.0.1a"
    }
    
    public func fileExists(name: String, type: String) -> Bool {
        let f = Bundle.module.url(forResource: name, withExtension: type)
        return f != nil
    }
    
    public func fileExistsInApp(name: String, type: String) -> Bool {
        let f = Bundle.main.url(forResource: name, withExtension: type)
        return f != nil
    }
}