fix for "" auto backends

Author: nmwsharp

src/render/initialize_backend.cpp

@@ -28,6 +28,11 @@ void initializeRenderEngine();
 
 void initializeRenderEngine(std::string backend) {
 
+  // Handle default backends
+  if (backend == "") {
+    backend = "auto"; // treat "" as "auto"
+  }
+  
   // Quick check to print a nice error for a bad name
   std::vector<std::string> knownBackendNames = {"openGL3_glfw", "openGL3_egl", "openGL_mock", "auto"};
   if (std::find(knownBackendNames.begin(), knownBackendNames.end(), backend) == knownBackendNames.end()) {
@@ -37,11 +42,6 @@ void initializeRenderEngine(std::string backend) {
     exception("unrecognized Polyscope backend " + backend + ". Known backend names are: " + namesConcat);
   }
 
-  // Handle default backends
-  if (backend == "") {
-    backend = "auto"; // treat "" as "auto"
-  }
-
   engineBackendName = backend;
 
   // Initialize the appropriate backend