Systems, methods, and computer readable media for collecting run-time error information for an executing script through the use of a double code-injection technique are described. A first native code injection into a user's client-side application (e.g., a browser application) is made. The second injection is thereafter made by the user's client-side application itself (when the first injected program code is executed) into the application's associated scripting engine and only when a script error has been detected. The second injected program code or scripts collect detailed run-time script error information within the context of the application's scripting engine. The second injected program code can then return the collected error information to the user application's context where it may be provided to a debug tool or recorded for later review (by the first injected program code).