[Windows]Fix NullReferenceException in OpenReadAsync for FileResult created with full path

src/Essentials/src/FileSystem/FileSystem.windows.cs

@@ -101,8 +101,15 @@ void PlatformInit(FileBase file)
 		// we can't do anything here, but Windows will take care of it
 		string PlatformGetContentType(string extension) => null;
 
-		internal virtual Task<Stream> PlatformOpenReadAsync() =>
-			File.OpenStreamForReadAsync();
+		internal async virtual Task<Stream> PlatformOpenReadAsync()
+		{
+			if (File is null && FullPath is not null)
+			{
+				File = await StorageFile.GetFileFromPathAsync(FullPath);
+			}
+
+			return await File.OpenStreamForReadAsync();
+		}
 	}
 
 	public partial class FileResult

src/Essentials/test/DeviceTests/Tests/FileSystem_Tests.cs

@@ -57,5 +57,49 @@ public async Task ValidateMIMEFormat()
 			File.Delete(filePath);
 		}
 #endif
+		[Fact]
+		public async Task CheckFileResultWithFilePath()
+		{
+			string filePath = Path.Combine(FileSystem.CacheDirectory, "sample.txt");
+			await File.WriteAllTextAsync(filePath, "Sample content for testing");
+
+			var fileResult = new FileResult(filePath);
+
+			using var stream = await fileResult.OpenReadAsync();
+
+			Assert.NotNull(stream);
+
+			File.Delete(filePath);
+		}
+
+		[Fact]
+		public async Task CheckFileResultOpenReadAsyncMultipleTimes()
+		{
+			string filePath = Path.Combine(FileSystem.CacheDirectory, "sample_multiple.txt");
+			string expectedContent = "Sample content for multiple stream testing";
+			await File.WriteAllTextAsync(filePath, expectedContent);
+
+			var fileResult = new FileResult(filePath);
+
+			// First call to OpenReadAsync
+			using (var firstStream = await fileResult.OpenReadAsync())
+			{
+				Assert.NotNull(firstStream);
+				using var firstReader = new StreamReader(firstStream);
+				var firstContent = await firstReader.ReadToEndAsync();
+				Assert.Equal(expectedContent, firstContent);
+			}
+
+			// Second call to OpenReadAsync - should still work
+			using (var secondStream = await fileResult.OpenReadAsync())
+			{
+				Assert.NotNull(secondStream);
+				using var secondReader = new StreamReader(secondStream);
+				var secondContent = await secondReader.ReadToEndAsync();
+				Assert.Equal(expectedContent, secondContent);
+			}
+
+			File.Delete(filePath);
+		}
 	}
 }