# AUR0778

**Note:** This error code does not appear to be actively used in the current version of the `runtime-html` package. This documentation is based on the error message string and may not reflect an actual runtime scenario.

## Error Message

`AUR0778: Unsupported: [repeat] cannot count <value>`

Where `<value>` is the string representation of the value whose count could not be determined.

## Description

This error likely indicates an internal state issue within the `repeat` controller where it attempted to determine the size or length of the collection being iterated over, but the collection was in a state or of a type where its count could not be retrieved (e.g., lacking a `length` or `size` property).

## Cause

(Speculative, as the error is not currently thrown) This might have occurred if the repeater's internal logic expected a collection with a countable property (like `.length` for Arrays/strings or `.size` for Maps/Sets) but encountered an unusual iterable or state where this property was missing or inaccessible.

## Solution

(Speculative)

* Ensure the collection bound to `repeat.for` consistently maintains its expected type (Array, Map, Set, string, number).
* If using custom iterables, ensure they behave predictably and don't enter states where their conceptual "size" cannot be determined if required by internal repeater logic.
* Given this error isn't currently thrown, if you encounter it, it might indicate a bug in the version of Aurelia being used or an interaction with unusual custom elements/attributes. Report it as an issue with detailed reproduction steps.

## Example

(N/A - Cannot provide a specific example as the error is not actively thrown)

## Debugging Tips

* Verify the collection bound to `repeat.for` is a standard, supported type.
* Check for any custom logic or integrations that might interfere with the repeater's handling of the collection.
* If this error appears unexpectedly, consider filing a bug report with Aurelia.