diff --git a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationState.ts b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationState.ts
index 417a9df2..b525c0df 100644
--- a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationState.ts
+++ b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationState.ts
@@ -24,7 +24,6 @@ export async function evaluateExpectationState(
 	const tracker: ExpectationTracker = runner.tracker
 
 	const timeSinceLastEvaluation = Date.now() - trackedExp.lastEvaluationTime
-	if (!trackedExp.session) trackedExp.session = {}
 	if (trackedExp.session.hadError) return // There was an error during the session.
 
 	if (trackedExp.session.expectationCanBeRemoved) return // The expectation has been removed
diff --git a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/aborted.ts b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/aborted.ts
index bc50c532..db383140 100644
--- a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/aborted.ts
+++ b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/aborted.ts
@@ -14,7 +14,6 @@ export async function evaluateExpectationStateAborted({
 }: EvaluateContext): Promise<void> {
 	assertState(trackedExp, ExpectedPackageStatusAPI.WorkStatusState.ABORTED)
 
-	if (!trackedExp.session) trackedExp.session = {}
 	await manager.workerAgents.assignWorkerToSession(trackedExp)
 	if (trackedExp.session.assignedWorker) {
 		// Start by removing the expectation
diff --git a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/fulfilled.ts b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/fulfilled.ts
index 2008f750..44ab3126 100644
--- a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/fulfilled.ts
+++ b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/fulfilled.ts
@@ -20,7 +20,6 @@ export async function evaluateExpectationStateFulfilled({
 	// TODO: Some monitor that is able to invalidate if it isn't fulfilled anymore?
 
 	if (timeSinceLastEvaluation > tracker.getFulfilledWaitTime()) {
-		if (!trackedExp.session) trackedExp.session = {}
 		await manager.workerAgents.assignWorkerToSession(trackedExp)
 		if (trackedExp.session.assignedWorker) {
 			try {
diff --git a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/ready.ts b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/ready.ts
index cd0487a4..8f84fe70 100644
--- a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/ready.ts
+++ b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/ready.ts
@@ -17,7 +17,6 @@ export async function evaluateExpectationStateReady({
 }: EvaluateContext): Promise<void> {
 	assertState(trackedExp, ExpectedPackageStatusAPI.WorkStatusState.READY)
 	// Start working on it:
-	if (!trackedExp.session) trackedExp.session = {}
 	await manager.workerAgents.assignWorkerToSession(trackedExp)
 
 	if (
diff --git a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/removed.ts b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/removed.ts
index 843c611e..0b6d681e 100644
--- a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/removed.ts
+++ b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/removed.ts
@@ -17,7 +17,6 @@ export async function evaluateExpectationStateRemoved({
 	/** When true, the expectation can be removed */
 	let removeTheExpectation = false
 
-	if (!trackedExp.session) trackedExp.session = {}
 	await manager.workerAgents.assignWorkerToSession(trackedExp)
 	if (trackedExp.session.assignedWorker) {
 		const removed = await trackedExp.session.assignedWorker.worker.removeExpectation(trackedExp.exp)
diff --git a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/restarted.ts b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/restarted.ts
index 12eee9e3..3366047a 100644
--- a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/restarted.ts
+++ b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/restarted.ts
@@ -13,7 +13,6 @@ export async function evaluateExpectationStateRestarted({
 }: EvaluateContext): Promise<void> {
 	assertState(trackedExp, ExpectedPackageStatusAPI.WorkStatusState.RESTARTED)
 
-	if (!trackedExp.session) trackedExp.session = {}
 	await manager.workerAgents.assignWorkerToSession(trackedExp)
 	if (trackedExp.session.assignedWorker) {
 		// Start by removing the expectation
diff --git a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/waiting.ts b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/waiting.ts
index ade07e31..20b0bda5 100644
--- a/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/waiting.ts
+++ b/shared/packages/expectationManager/src/evaluationRunner/evaluateExpectationStates/waiting.ts
@@ -19,7 +19,6 @@ export async function evaluateExpectationStateWaiting({
 	assertState(trackedExp, ExpectedPackageStatusAPI.WorkStatusState.WAITING)
 
 	// Check if the expectation is ready to start:
-	if (!trackedExp.session) trackedExp.session = {}
 	await manager.workerAgents.assignWorkerToSession(trackedExp)
 
 	if (trackedExp.session.assignedWorker) {
diff --git a/shared/packages/expectationManager/src/evaluationRunner/evaluationRunner.ts b/shared/packages/expectationManager/src/evaluationRunner/evaluationRunner.ts
index 7d84d5d2..94cfec0c 100644
--- a/shared/packages/expectationManager/src/evaluationRunner/evaluationRunner.ts
+++ b/shared/packages/expectationManager/src/evaluationRunner/evaluationRunner.ts
@@ -278,7 +278,7 @@ export class EvaluationRunner {
 
 		// Step 0: Reset the session:
 		for (const trackedExp of tracked) {
-			trackedExp.session = null
+			trackedExp.session = {}
 		}
 
 		const postProcessSession = (trackedExp: TrackedExpectation) => {
@@ -343,7 +343,7 @@ export class EvaluationRunner {
 		// Step 1.5: Reset the session:
 		// Because during the next iteration, the worker-assignment need to be done in series
 		for (const trackedExp of tracked) {
-			trackedExp.session = null
+			trackedExp.session = {}
 		}
 
 		this.logger.debug(`Handle other states..`)
diff --git a/shared/packages/expectationManager/src/expectationTracker/lib/trackedExpectationAPI.ts b/shared/packages/expectationManager/src/expectationTracker/lib/trackedExpectationAPI.ts
index ce02c0eb..da0cb1a4 100644
--- a/shared/packages/expectationManager/src/expectationTracker/lib/trackedExpectationAPI.ts
+++ b/shared/packages/expectationManager/src/expectationTracker/lib/trackedExpectationAPI.ts
@@ -170,7 +170,6 @@ export class TrackedExpectationAPI {
 	 * Handle an Expectation that had no worker assigned
 	 */
 	public noWorkerAssigned(trackedExp: TrackedExpectation): void {
-		if (!trackedExp.session) throw new Error('Internal error: noWorkerAssigned: session not set')
 		if (trackedExp.session.assignedWorker)
 			throw new Error('Internal error: noWorkerAssigned can only be called when assignedWorker is falsy')
 
diff --git a/shared/packages/expectationManager/src/lib/trackedExpectation.ts b/shared/packages/expectationManager/src/lib/trackedExpectation.ts
index 8ee2ce44..92b77a0c 100644
--- a/shared/packages/expectationManager/src/lib/trackedExpectation.ts
+++ b/shared/packages/expectationManager/src/lib/trackedExpectation.ts
@@ -54,8 +54,8 @@ export interface TrackedExpectation {
 		targetCanBeUsedWhileTransferring?: boolean
 		sourceIsPlaceholder?: boolean
 	}
-	/** A storage which is persistant only for a short while, during an evaluation of the Expectation. */
-	session: ExpectationStateHandlerSession | null
+	/** A storage which is persistent only for a short while, during an evaluation of the Expectation. */
+	session: ExpectationStateHandlerSession
 }
 
 export function expLabel(exp: TrackedExpectation): string {
@@ -120,6 +120,6 @@ export function getDefaultTrackedExpectation(
 		},
 		prevStatusReasons: existingtrackedExp?.prevStatusReasons || {},
 		status: {},
-		session: null,
+		session: {},
 	}
 }