12 Testcases under jdk/incubator/vector/* get `java.lang.NullPointerException: Cannot load from short array because "vec2" is null` with jdk25 on AIX

TEST: jdk/incubator/vector/Byte64VectorLoadStoreTests.java
TEST: jdk/incubator/vector/Byte64VectorTests.java
TEST: jdk/incubator/vector/ByteMaxVectorLoadStoreTests.java
TEST: jdk/incubator/vector/ByteMaxVectorTests.java
TEST: jdk/incubator/vector/Float64VectorTests.java
TEST: jdk/incubator/vector/FloatMaxVectorTests.java
TEST: jdk/incubator/vector/Int64VectorLoadStoreTests.java
TEST: jdk/incubator/vector/Int64VectorTests.java
TEST: jdk/incubator/vector/IntMaxVectorTests.java
TEST: jdk/incubator/vector/Short64VectorTests.java
TEST: jdk/incubator/vector/ShortMaxVectorTests.java

error message

```
23:49:29 test ShortMaxVectorTests.unsliceShortMaxVectorTestsMasked(short[-i * 5], short[i * 5], mask[i % 2]): failure [10ms]
23:49:29 java.lang.NullPointerException: Cannot load from short array because "vec2" is null
23:49:29 at jdk.incubator.vector/jdk.incubator.vector.ShortVector.bTest(ShortVector.java:476)
23:49:29 at jdk.incubator.vector/jdk.incubator.vector.ShortVector.lambda$compareTemplate$0(ShortVector.java:2078)
23:49:29 at java.base/jdk.internal.vm.vector.VectorSupport.compare(VectorSupport.java:602)
23:49:29 at jdk.incubator.vector/jdk.incubator.vector.ShortVector.compareTemplate(ShortVector.java:2073)
23:49:29 at jdk.incubator.vector/jdk.incubator.vector.ShortMaxVector.compare(ShortMaxVector.java:384)
23:49:29 at jdk.incubator.vector/jdk.incubator.vector.ShortMaxVector.compare(ShortMaxVector.java:43)
23:49:29 at jdk.incubator.vector/jdk.incubator.vector.ShortVector.unsliceTemplate(ShortVector.java:2370)
23:49:29 at jdk.incubator.vector/jdk.incubator.vector.ShortVector.unsliceTemplate(ShortVector.java:2385)
23:49:29 at jdk.incubator.vector/jdk.incubator.vector.ShortMaxVector.unslice(ShortMaxVector.java:437)
23:49:29 at jdk.incubator.vector/jdk.incubator.vector.ShortMaxVector.unslice(ShortMaxVector.java:43)
23:49:29 at ShortMaxVectorTests.unsliceShortMaxVectorTestsMasked(ShortMaxVectorTests.java:5548)
23:49:29 at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
23:49:29 at java.base/java.lang.reflect.Method.invoke(Method.java:565)
23:49:29 at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:132)
23:49:29 at org.testng.internal.TestInvoker.invokeMethod(TestInvoker.java:599)
23:49:29 at org.testng.internal.TestInvoker.invokeTestMethod(TestInvoker.java:174)
23:49:29 at org.testng.internal.MethodRunner.runInSequence(MethodRunner.java:46)
23:49:29 at org.testng.internal.TestInvoker$MethodInvocationAgent.invoke(TestInvoker.java:822)
23:49:29 at org.testng.internal.TestInvoker.invokeTestMethods(TestInvoker.java:147)
23:49:29 at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:146)
23:49:29 at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:128)
23:49:29 at java.base/java.util.ArrayList.forEach(ArrayList.java:1604)
```

Might be related with https://bugs.openjdk.org/browse/JDK-8354383 - help needed to confirm.

Start with ShortMaxVectorTests.java at line 5548 and the other listed jdk/incubator/vector tests, then trace the failure through ShortVector.java bTest and unsliceTemplate. Compare the AIX jdk25 behavior with JDK-8354383; done means confirming whether the issues share a cause and documenting or fixing the failure so the affected tests pass.

Written by the indexing model from the issue text.