Do not crash when reading null planets

core/src/mindustry/editor/EditorTool.java

@@ -106,7 +106,7 @@ public enum EditorTool{
 
             if(tile == null) return;
 
-            if(editor.drawBlock.isMultiblock()){
+            if(editor.drawBlock.isMultiblock() && (mode == 0 || mode == -1)){
                 //don't fill multiblocks, thanks
                 pencil.touched(x, y);
                 return;

core/src/mindustry/io/JsonIO.java

@@ -195,6 +195,9 @@ public class JsonIO{
 
             @Override
             public Planet read(Json json, JsonValue jsonData, Class type){
+                if(jsonData.asString() == null){
+                    return null;
+                }
                 Planet block = Vars.content.getByName(ContentType.planet, jsonData.asString());
                 return block == null ? Planets.serpulo : block;
             }