[flutter_tools] Unhandled DartDevelopmentServiceException when WebSocket upgrade fails during DDS startup in ResidentWebRunner #191179

Summary

In Flutter 3.47.0 telemetry, an unhandled DartDevelopmentServiceException during web debugging startup emerged as a top crash signature.

When DDS fails to upgrade its WebSocket connection to DWDS (e.g., due to early browser termination or socket closure), package:dds throws DartDevelopmentServiceException with error code connectionError (Code 3). Because ResidentWebRunner.run() only handled failedToStartError and re-threw other error codes, the exception escaped unhandled and crashed the tool.

Telemetry Profile

• Release: Flutter 3.47.0 (Top 10 crasher)
• Signature: DartDevelopmentServiceException-53f282da

Error Output

DartDevelopmentServiceException: WebSocketChannelException: WebSocketException: Connection to 'http://127.0.0.1:62932/9fVOXxsamo0=/ws#' was not upgraded to websocket

Root Cause

In packages/flutter_tools/lib/src/isolated/resident_web_runner.dart, the on DartDevelopmentServiceException handler checked:

if (error.errorCode == DartDevelopmentServiceException.failedToStartError) {
  throwToolExit(kExitMessage);
}
rethrow;

When WebSocket upgrade failed, package:dds threw DartDevelopmentServiceException.connectionIssue() with errorCode == DartDevelopmentServiceException.connectionError (3). The condition evaluated to false, hitting rethrow; and crashing the tool.

Proposed Fix

Update on DartDevelopmentServiceException in ResidentWebRunner.run() to catch all DDS exception variants, log error diagnostics with stack trace, call appFailedToStart(), and gracefully exit via throwToolExit(kExitMessage) without rethrowing.