[NPU] fix segfault in compile_tool (#28434)

### Details:
- Fix `Segmentation fault (core dumped)` issue when running
`compile_tool` without a device.
 
### Tickets:
 - *E151581*

src/plugins/intel_npu/src/compiler_adapter/include/compiler_adapter_factory.hpp

@@ -19,14 +19,13 @@ class CompilerAdapterFactory final {
         auto compilerType = config.get<COMPILER_TYPE>();
         switch (compilerType) {
         case ov::intel_npu::CompilerType::MLIR: {
-            if (engineBackend->getName() != "LEVEL0") {
+            if (engineBackend == nullptr || engineBackend->getName() != "LEVEL0") {
                 return std::make_unique<PluginCompilerAdapter>(nullptr);
             }
-
             return std::make_unique<PluginCompilerAdapter>(engineBackend->getInitStructs());
         }
         case ov::intel_npu::CompilerType::DRIVER: {
-            if (engineBackend->getName() != "LEVEL0") {
+            if (engineBackend == nullptr || engineBackend->getName() != "LEVEL0") {
                 OPENVINO_THROW("NPU Compiler Adapter must be used with LEVEL0 backend");
             }