Crash fixes

core/src/io/anuke/mindustry/core/Control.java

@@ -373,7 +373,9 @@ public class Control implements ApplicationListener, Loadable{
     public void update(){
         saves.update();
         //update and load any requested assets
-        assets.update();
+        if(assets != null){
+            assets.update();
+        }
 
         input.updateController();
 

core/src/io/anuke/mindustry/maps/MapPreviewLoader.java

@@ -5,6 +5,7 @@ import io.anuke.arc.assets.loaders.*;
 import io.anuke.arc.assets.loaders.resolvers.*;
 import io.anuke.arc.collection.*;
 import io.anuke.arc.files.*;
+import io.anuke.arc.graphics.*;
 import io.anuke.mindustry.*;
 import io.anuke.mindustry.game.*;
 
@@ -25,6 +26,21 @@ public class MapPreviewLoader extends TextureLoader{
         }
     }
 
+    @Override
+    public Texture loadSync(AssetManager manager, String fileName, FileHandle file, TextureParameter parameter){
+        try{
+            return super.loadSync(manager, fileName, file, parameter);
+        }catch(Throwable e){
+            e.printStackTrace();
+            try{
+                return new Texture(file);
+            }catch(Throwable e2){
+                e2.printStackTrace();
+                return new Texture("sprites/error.png");
+            }
+        }
+    }
+
     @Override
     public Array<AssetDescriptor> getDependencies(String fileName, FileHandle file, TextureParameter parameter){
         return Array.with(new AssetDescriptor<>("contentcreate", Content.class));