egametang/ET · critical · Exception

condition variable node must inherit BTCondition: {type.Full

Error message

condition variable node must inherit BTCondition: {type.FullName}

What it means

Thrown during ConditionVariableRegistry.Awake() while scanning every type decorated with [ConditionVariable]. Every such type must be assignable to BTCondition because the parser later instantiates it as `Activator.CreateInstance(nodeType) as BTCondition`. A type that is not a BTCondition cannot be cast and would fail later, so registration aborts early.

Source

Thrown at Packages/cn.etetet.conditionexpr/Scripts/Model/Share/ConditionVariableRegistry.cs:22

namespace ET
{
    [CodeProcess]
    [AllowInstance]
    public class ConditionVariableRegistry : Singleton<ConditionVariableRegistry>, ISingletonAwake
    {
        private readonly Dictionary<string, Type> variableNodeTypes = new();
        private readonly Dictionary<string, NumericType> numericTypes = new();

        public void Awake()
        {
            this.RegisterNumericTypes();
            
            HashSet<Type> types = CodeTypes.Instance.GetTypes(typeof(ConditionVariableAttribute));
            foreach (Type type in types)
            {
                if (!typeof(BTCondition).IsAssignableFrom(type))
                {
                    throw new Exception($"condition variable node must inherit BTCondition: {type.FullName}");
                }

                object[] attrs = type.GetCustomAttributes(typeof(ConditionVariableAttribute), false);
                foreach (object attr in attrs)
                {
                    ConditionVariableAttribute conditionVariableAttribute = (ConditionVariableAttribute)attr;
                    if (string.IsNullOrWhiteSpace(conditionVariableAttribute.Variable))
                    {
                        throw new Exception($"condition variable is empty: {type.FullName}");
                    }

                    if (!this.variableNodeTypes.TryAdd(conditionVariableAttribute.Variable, type))
                    {
                        throw new Exception($"duplicate condition variable: {conditionVariableAttribute.Variable}");
                    }
                }
            }
        }

View on GitHub (pinned to 5cab01f7a8)

Solutions

1. Make the attributed class derive from BTCondition (directly or transitively).
2. Remove [ConditionVariable] from the offending type if it is not actually a condition node.
3. Rebuild/re-scan so CodeTypes.Instance picks up the corrected inheritance.

Example fix

// before
[ConditionVariable("MyVar")]
public class MyVarNode : BTNode { }
// after
[ConditionVariable("MyVar")]
public class MyVarNode : BTCondition { }

// in a bootstrap test
foreach (Type t in CodeTypes.Instance.GetTypes(typeof(ConditionVariableAttribute)))
{
    if (!typeof(BTCondition).IsAssignableFrom(t))
        Assert.Fail($"{t.FullName} must inherit BTCondition");
}

static bool IsConditionNode(Type t) => typeof(BTCondition).IsAssignableFrom(t);

When it happens

Trigger: Applying [ConditionVariable("X")] to a plain class, struct, or a BehaviorTree node that derives from BTNode but not BTCondition; adding the attribute to a data/DTO class by mistake.

Common situations: A developer copies the attribute onto a helper/utility class; a node was refactored to inherit a different base and no longer satisfies BTCondition.

Related errors

• condition variable is empty: {type.FullName}
• duplicate condition variable: {conditionVariableAttribute.Va
• ConsoleHandler handler not inherit IConsoleHandler class: {o
• condition node field not found: {node.GetType().FullName}.{f
• condition node owner key field not found: {node.GetType().Fu

AI-assisted analysis of egametang/ET@5cab01f7a8 (2026-08-13). Data as JSON: /api/errors/69ccc3f88ecee4da. Report an issue: GitHub.