Fix crash on serializing space teams (#3726)

(cherry picked from commit 81d63a5)

src/main/java/gregtech/common/misc/spaceprojects/SpaceProjectWorldSavedData.java

@@ -207,6 +207,7 @@ private static class SpaceTeamAdapter
         public JsonElement serialize(HashMap<UUID, UUID> src, Type typeOfSrc, JsonSerializationContext context) {
             JsonArray map = new JsonArray();
             for (Entry<UUID, UUID> entry : src.entrySet()) {
+                if (entry.getKey() == null) continue;
                 JsonObject teamMap = new JsonObject();
 
                 teamMap.addProperty(