Fix OrDefault methods to return default values instead of throwing exceptions

csharp/Platform.IO.Tests/FileHelpersTests.cs

@@ -15,5 +15,33 @@ public void WriteReadTest()
             Assert.Equal(readValue, originalValue);
             File.Delete(temporaryFile);
         }
+
+        [Fact]
+        public void ReadFirstOrDefaultShouldReturnDefaultForMisalignedFile()
+        {
+            var temporaryFile = Path.GetTempFileName();
+            // Write 5 bytes to create a file that's not aligned to ulong (8 bytes)
+            File.WriteAllBytes(temporaryFile, new byte[] { 1, 2, 3, 4, 5 });
+
+            // This should return default(ulong) = 0, not throw an exception
+            var result = FileHelpers.ReadFirstOrDefault<ulong>(temporaryFile);
+            Assert.Equal(0UL, result);
+
+            File.Delete(temporaryFile);
+        }
+
+        [Fact]
+        public void ReadLastOrDefaultShouldReturnDefaultForMisalignedFile()
+        {
+            var temporaryFile = Path.GetTempFileName();
+            // Write 5 bytes to create a file that's not aligned to ulong (8 bytes)
+            File.WriteAllBytes(temporaryFile, new byte[] { 1, 2, 3, 4, 5 });
+
+            // This should return default(ulong) = 0, not throw an exception
+            var result = FileHelpers.ReadLastOrDefault<ulong>(temporaryFile);
+            Assert.Equal(0UL, result);
+
+            File.Delete(temporaryFile);
+        }
     }
 }

csharp/Platform.IO/FileHelpers.cs

@@ -85,7 +85,7 @@ private static FileStream GetValidFileStreamOrDefault(string path, int elementSi
             var fileSize = GetSize(path);
             if (fileSize % elementSize != 0)
             {
-                throw new InvalidOperationException($"File is not aligned to elements with size {elementSize}.");
+                return null;
             }
             return fileSize > 0 ? File.OpenRead(path) : null;
         }