Fixed VerifyDebugUsage test.

Author: tzezula

compiler/src/jdk.graal.compiler.test/src/jdk/graal/compiler/core/test/VerifyDebugUsage.java

@@ -203,7 +203,9 @@ protected int verifyDumpLevelParameter(MethodCallTargetNode debugCallTarget, Res
     protected void verifyDumpObjectParameter(MethodCallTargetNode debugCallTarget, ValueNode arg, ResolvedJavaMethod verifiedCallee, Integer dumpLevel)
                     throws VerifyPhase.VerificationError {
         ResolvedJavaType argType = ((ObjectStamp) arg.stamp(NodeView.DEFAULT)).type();
-        if (metaAccess.lookupJavaType(Graph.class).isAssignableFrom(argType)) {
+        // GR-64309: Calls returning interface type are built with an unrestricted stamp. ArgType is
+        // null for SubstrateInstalledCode.
+        if (argType != null && metaAccess.lookupJavaType(Graph.class).isAssignableFrom(argType)) {
             verifyStructuredGraphDumping(debugCallTarget, verifiedCallee, dumpLevel);
         }
     }