Fix minor issues with show_entity hover in messages (#3908)

* actually use show entity hover event type, instead of using name in the wrong place

* don't attempt to getString of null resources when showing entity type in hover

EntityList does not contain all possible entity types. It does not contain entries for:
FishingHook, lightning, Weather, Player, or ComplexPart.
Trying to use a hover show entity of one of these types would cause a null pointer exception.
And before the previous commit the type was actually the name.
Which caused showing entities with a name of "Player" or one of the other types mentioned above to cause this error.
Preventing the message from being sent.

src/main/java/org/spongepowered/common/mixin/core/util/text/event/HoverEventMixin.java

@@ -71,7 +71,7 @@ public abstract class HoverEventMixin implements HoverEventBridge {
                         String name = nbt.getString("name");
                         EntityType type = null;
                         if (nbt.hasKey("type", Constants.NBT.TAG_STRING)) {
-                            type = SpongeImpl.getGame().getRegistry().getType(EntityType.class, name).orElse(null);
+                            type = SpongeImpl.getGame().getRegistry().getType(EntityType.class, nbt.getString("type")).orElse(null);
                         }
 
                         UUID uniqueId = UUID.fromString(nbt.getString("id"));

src/main/java/org/spongepowered/common/text/action/SpongeHoverAction.java

@@ -27,6 +27,7 @@
 import net.minecraft.entity.EntityList;
 import net.minecraft.item.ItemStack;
 import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.util.ResourceLocation;
 import net.minecraft.util.text.ITextComponent;
 import net.minecraft.util.text.TextComponentString;
 import net.minecraft.util.text.event.HoverEvent;
@@ -66,7 +67,10 @@ public static HoverEvent getHandle(HoverAction<?> action) {
                 nbt.setString("id", entity.getUniqueId().toString());
 
                 if (entity.getType().isPresent()) {
-                    nbt.setString("type", EntityList.getKey(((SpongeEntityType) entity.getType().get()).entityClass).toString());
+                    ResourceLocation resource = EntityList.getKey(((SpongeEntityType) entity.getType().get()).entityClass);
+                    if (resource != null) {
+                        nbt.setString("type", resource.toString());
+                    }
                 }
 
                 nbt.setString("name", entity.getName());