fix getLastErrorText

java/cuvs-java/src/main/java22/com/nvidia/cuvs/internal/common/Util.java

@@ -67,6 +67,9 @@ public static void checkError(int value, String caller) {
   static String getLastErrorText() {
     try {
       MemorySegment seg = (MemorySegment) getLastErrorTextMethodHandle.invokeExact();
+      if (seg.equals(MemorySegment.NULL)) {
+        return "no last error text";
+      }
       return seg.reinterpret(MAX_ERROR_TEXT).getString(0L);
     } catch (Throwable t) {
       throw new RuntimeException(t);

java/cuvs-java/src/test/java/com/nvidia/cuvs/CuVSTestCase.java

@@ -101,7 +101,7 @@ protected void compareResults(SearchResults results, List<List<Integer>> expecte
     }
   }
 
-  static boolean isLinuxAmd64() {
+  protected static boolean isLinuxAmd64() {
     String name = System.getProperty("os.name");
     return (name.startsWith("Linux")) && System.getProperty("os.arch").equals("amd64");
   }

java/cuvs-java/src/test/java/com/nvidia/cuvs/internal/common/UtilIT.java

@@ -0,0 +1,37 @@
+package com.nvidia.cuvs.internal.common;
+
+import com.nvidia.cuvs.CuVSTestCase;
+import org.junit.Before;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+
+import static com.carrotsearch.randomizedtesting.RandomizedTest.assumeTrue;
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+public class UtilIT extends CuVSTestCase {
+
+  private static final Logger log = LoggerFactory.getLogger(UtilIT.class);
+
+  @Before
+  public void setup() {
+    assumeTrue("not supported on " + System.getProperty("os.name"), isLinuxAmd64());
+  }
+
+  @Test
+  public void testGetLastErrorText() throws Throwable {
+    var cls = Class.forName("com.nvidia.cuvs.internal.common.Util");
+    var lookup = MethodHandles.lookup();
+    var mt = MethodType.methodType(String.class);
+    var mh = lookup.findStatic(cls, "getLastErrorText", mt);
+
+    // first, ensures that accessing the error text when there is none does not crash!
+    String errorText = (String) mh.invoke();
+    // second, ensures that the default test is returned
+    assertThat(errorText, equalTo("no last error text"));
+  }
+}