fix(error-interception): add null guard to getTaskState to prevent WeakMap crash

Author: Zoo (VP)

src/core/tools/error-interception/ToolErrorInterceptor.ts

@@ -89,8 +89,18 @@ export class ToolErrorInterceptor {
 	/**
 	 * Creates or returns existing per-task state. Uses a WeakMap keyed by the
 	 * Task object so state is discarded when the task is garbage collected.
+	 *
+	 * When `task` is null or undefined (invalid WeakMap key), returns an
+	 * ephemeral default state to satisfy the fail-open philosophy rather than
+	 * throwing TypeError from WeakMap.set().
 	 */
 	public getTaskState(task: object): InterceptorTaskState {
+		// WeakMap keys must be objects; null/undefined are invalid and would
+		// throw TypeError on .set(). Fail-open: return an ephemeral default
+		// state so callers can proceed without crashing.
+		if (!task) {
+			return { categoryCounts: new Map(), shellCircuitOpen: false }
+		}
 		let taskState = this.state.perTask.get(task)
 		if (!taskState) {
 			taskState = { categoryCounts: new Map(), shellCircuitOpen: false }