Fix item effects conversion if no tag is present

Fixes #9796

patches/server/0015-Rewrite-dataconverter-system.patch

@@ -19145,10 +19145,10 @@ index 0000000000000000000000000000000000000000..2501759bc1c0313c0556d4f75a0c4a3d
 +}
 diff --git a/src/main/java/ca/spottedleaf/dataconverter/minecraft/versions/V3568.java b/src/main/java/ca/spottedleaf/dataconverter/minecraft/versions/V3568.java
 new file mode 100644
-index 0000000000000000000000000000000000000000..98272d556a09e9f035005c6783ebb229c2c7157d
+index 0000000000000000000000000000000000000000..311a57529c5f95ce48631b48fefb4ebae401b3f7
 --- /dev/null
 +++ b/src/main/java/ca/spottedleaf/dataconverter/minecraft/versions/V3568.java
-@@ -0,0 +1,239 @@
+@@ -0,0 +1,243 @@
 +package ca.spottedleaf.dataconverter.minecraft.versions;
 +
 +import ca.spottedleaf.dataconverter.converters.DataConverter;
@@ -19352,6 +19352,10 @@ index 0000000000000000000000000000000000000000..98272d556a09e9f035005c6783ebb229
 +
 +                final MapType<String> tag = root.getMap("tag");
 +
++                if (tag == null) {
++                    return null;
++                }
++
 +                if ("minecraft:suspicious_stew".equals(id)) {
 +                    RenameHelper.renameSingle(tag, "Effects", "effects");
 +