Fix crash in OpenSpaceTest due to missing initialization of the LogManager

tests/main.cpp

@@ -42,9 +42,14 @@
 
 int main(int argc, char** argv) {
     using namespace openspace;
+
+    ghoul::logging::LogManager::initialize(
+        ghoul::logging::LogLevel::Debug,
+        ghoul::logging::LogManager::ImmediateFlush::Yes
+    );
     ghoul::initialize();
     global::create();
-    
+
     // Register the path of the executable,
     // to make it possible to find other files in the same directory.
     FileSys.registerPathToken(