Avoid crashing when failing graphics VTS

When the tests fail, ensure we continue running so we can run the
remainder of the tests.

Bug: 304976052
Test: atest GraphicsComposerAidlCommandTest
Change-Id: Ia6ab2bbd284bb7eddeb49164dcbe7285829ad9c3
diff --git a/graphics/composer/aidl/vts/VtsComposerClient.cpp b/graphics/composer/aidl/vts/VtsComposerClient.cpp
index 2c24bfb..89ba2e6 100644
--- a/graphics/composer/aidl/vts/VtsComposerClient.cpp
+++ b/graphics/composer/aidl/vts/VtsComposerClient.cpp
@@ -68,6 +68,9 @@
 
 std::pair<ScopedAStatus, int32_t> VtsComposerClient::getInterfaceVersion() const {
     int32_t version = 1;
+    if (!mComposerClient) {
+        return {ScopedAStatus{nullptr}, version};
+    }
     auto status = mComposerClient->getInterfaceVersion(&version);
     return {std::move(status), version};
 }