Guard GetCanonicalPath against null

Signed-off-by: ahmad <ahmadalgaidy@hotmail.com>

Author: tomatotomata

src/Lucene.Net.Tests/Support/IO/TestFileSupport.cs

@@ -184,6 +184,14 @@ public void TestGetCanonicalPath()
             }
         }
 
+        [Test, LuceneNetSpecific]
+        public void TestGetCanonicalPathNullPath()
+        {
+            FileSystemInfo path = null;
+
+            Assert.Throws<ArgumentNullException>(() => path.GetCanonicalPath());
+        }
+
         private static string addTrailingSlash(string path)
         {
             if (Path.DirectorySeparatorChar == path[path.Length - 1])

src/Lucene.Net/Support/IO/FileSupport.cs

@@ -536,6 +536,11 @@ internal static string NewTempFileName(string prefix, string? suffix, string dir
         // LUCENENET NOTE: Implementation ported mostly from Apache Harmony
         public static string GetCanonicalPath(this FileSystemInfo path)
         {
+            if (path is null)
+            {
+                throw new ArgumentNullException(nameof(path));
+            }
+
             string absPath = path.FullName; // LUCENENET NOTE: This internally calls GetFullPath(), which resolves relative paths
             byte[] result = Encoding.UTF8.GetBytes(absPath);