public FunctionEvaluator setMissingValue(Tensor value) {
        if (evaluated)
            throw new IllegalStateException("Cannot change the missing value in a used evaluator");
        context.setMissingValue(value);
        return this;
    }
Sets the default value to use for variables which are not bound

@param value the default value
@return this for chaining
model-evaluation/src/main/java/ai/vespa/models/evaluation/FunctionEvaluator.java