This issue is one of the top crashers identified in the Flutter 3.44.3 stable release.

On secured Windows environments (using Windows Defender Application Control - WDAC or AppLocker), the execution of impellerc.exe is blocked by the OS, causing a fatal ProcessException and crashing the build with a raw stack trace.

Root Cause

Strict security policies block unsigned or user-directory binaries from executing. The tool does not catch this specific failure, leading to a raw crash.

Proposed Solution

1. Add detection for WDAC/AppLocker block exceptions (checking for error code 1260 and policy-related error text).
2. Log a highly visible, user-friendly boxed error message advising the user to contact their administrator to whitelist the binary.
3. Respect the fatal flag: throw a clean ToolExit during builds, but return false gracefully during interactive hot reload sessions to keep the session alive.