Check for null server ip on Fabric (#3842)

bootstrap/fabric/src/main/java/org/geysermc/geyser/platform/fabric/GeyserFabricMod.java

@@ -217,10 +217,12 @@ public class GeyserFabricMod implements ModInitializer, GeyserBootstrap {
         return this.server.getServerVersion();
     }
 
+    @SuppressWarnings("ConstantConditions") // IDEA thinks that ip cannot be null
     @NotNull
     @Override
     public String getServerBindAddress() {
-        return this.server.getLocalIp();
+        String ip = this.server.getLocalIp();
+        return ip != null ? ip : ""; // See issue #3812
     }
 
     @Override