Index: src/main/java/net/minecraft/server/JsonList.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/main/java/net/minecraft/server/JsonList.java b/src/main/java/net/minecraft/server/JsonList.java
--- a/src/main/java/net/minecraft/server/JsonList.java	(revision ec1b4311cebfd9bc35a5f84f56df46cf7319649a)
+++ b/src/main/java/net/minecraft/server/JsonList.java	(date 1609013366119)
@@ -156,6 +156,9 @@
     }
 
     public void save() throws IOException {
+        if(!this.c.canWrite())
+            return;
+
         Collection<V> collection = this.d.values();
         String s = this.b.toJson(collection);
         BufferedWriter bufferedwriter = null;