diff --git a/src/common/HTTPRequest.ts b/src/common/HTTPRequest.ts
index 70cd9650..cd57d3eb 100644
--- a/src/common/HTTPRequest.ts
+++ b/src/common/HTTPRequest.ts
@@ -120,11 +120,11 @@ export class HTTPRequest {
   /**
    * @internal
    */
-  _interceptionId: string;
+  _interceptionId: string | undefined;
   /**
    * @internal
    */
-  _failureText = null;
+  _failureText: string | null = null;
   /**
    * @internal
    */
@@ -148,7 +148,7 @@ export class HTTPRequest {
   private _method: string;
   private _postData?: string;
   private _headers: Record<string, string> = {};
-  private _frame: Frame;
+  private _frame: Frame | null;
   private _continueRequestOverrides: ContinueRequestOverrides;
   private _responseForRequest: Partial<ResponseForRequest> | null = null;
   private _abortErrorReason: Protocol.Network.ErrorReason | null = null;
@@ -163,8 +163,8 @@ export class HTTPRequest {
    */
   constructor(
     client: CDPSession,
-    frame: Frame,
-    interceptionId: string,
+    frame: Frame | null,
+    interceptionId: string | undefined,
     allowInterception: boolean,
     event: Protocol.Network.RequestWillBeSentEvent,
     redirectChain: HTTPRequest[]
@@ -476,6 +476,10 @@ export class HTTPRequest {
       ? Buffer.from(postData).toString('base64')
       : undefined;
 
+    if (this._interceptionId === undefined)
+      throw new Error(
+        'HTTPRequest is missing _interceptionId needed for Fetch.continueRequest'
+      );
     await this._client
       .send('Fetch.continueRequest', {
         requestId: this._interceptionId,
@@ -577,6 +581,10 @@ export class HTTPRequest {
       );
 
     const status = response.status || 200;
+    if (this._interceptionId === undefined)
+      throw new Error(
+        'HTTPRequest is missing _interceptionId needed for Fetch.fulfillRequest'
+      );
     await this._client
       .send('Fetch.fulfillRequest', {
         requestId: this._interceptionId,
@@ -634,6 +642,10 @@ export class HTTPRequest {
     errorReason: Protocol.Network.ErrorReason | null
   ): Promise<void> {
     this._interceptionHandled = true;
+    if (this._interceptionId === undefined)
+      throw new Error(
+        'HTTPRequest is missing _interceptionId needed for Fetch.failRequest'
+      );
     await this._client
       .send('Fetch.failRequest', {
         requestId: this._interceptionId,
diff --git a/src/common/NetworkEventManager.ts b/src/common/NetworkEventManager.ts
index 97431094..632a8f5a 100644
--- a/src/common/NetworkEventManager.ts
+++ b/src/common/NetworkEventManager.ts
@@ -97,14 +97,16 @@ export class NetworkEventManager {
     if (!this._responseReceivedExtraInfoMap.has(networkRequestId)) {
       this._responseReceivedExtraInfoMap.set(networkRequestId, []);
     }
-    return this._responseReceivedExtraInfoMap.get(networkRequestId);
+    return this._responseReceivedExtraInfoMap.get(
+      networkRequestId
+    ) as Protocol.Network.ResponseReceivedExtraInfoEvent[];
   }
 
   private queuedRedirectInfo(fetchRequestId: FetchRequestId): RedirectInfoList {
     if (!this._queuedRedirectInfoMap.has(fetchRequestId)) {
       this._queuedRedirectInfoMap.set(fetchRequestId, []);
     }
-    return this._queuedRedirectInfoMap.get(fetchRequestId);
+    return this._queuedRedirectInfoMap.get(fetchRequestId) as RedirectInfoList;
   }
 
   queueRedirectInfo(
diff --git a/src/common/NetworkManager.ts b/src/common/NetworkManager.ts
index 84efafa3..1f3c748e 100644
--- a/src/common/NetworkManager.ts
+++ b/src/common/NetworkManager.ts
@@ -86,7 +86,7 @@ export class NetworkManager extends EventEmitter {
   _networkEventManager = new NetworkEventManager();
 
   _extraHTTPHeaders: Record<string, string> = {};
-  _credentials?: Credentials = null;
+  _credentials?: Credentials;
   _attemptedAuthentications = new Set<string>();
   _userRequestInterceptionEnabled = false;
   _protocolRequestInterceptionEnabled = false;
@@ -275,7 +275,7 @@ export class NetworkManager extends EventEmitter {
 
       return;
     }
-    this._onRequest(event, null);
+    this._onRequest(event, undefined);
   }
 
   _onAuthRequired(event: Protocol.Fetch.AuthRequiredEvent): void {
@@ -368,7 +368,7 @@ export class NetworkManager extends EventEmitter {
     event: Protocol.Network.RequestWillBeSentEvent,
     fetchRequestId?: FetchRequestId
   ): void {
-    let redirectChain = [];
+    let redirectChain: HTTPRequest[] = [];
     if (event.redirectResponse) {
       // We want to emit a response and requestfinished for the
       // redirectResponse, but we can't do so unless we have a
@@ -406,6 +406,7 @@ export class NetworkManager extends EventEmitter {
     const frame = event.frameId
       ? this._frameManager.frame(event.frameId)
       : null;
+
     const request = new HTTPRequest(
       this._client,
       frame,
@@ -430,7 +431,7 @@ export class NetworkManager extends EventEmitter {
   _handleRequestRedirect(
     request: HTTPRequest,
     responsePayload: Protocol.Network.Response,
-    extraInfo: Protocol.Network.ResponseReceivedExtraInfoEvent
+    extraInfo: Protocol.Network.ResponseReceivedExtraInfoEvent | null
   ): void {
     const response = new HTTPResponse(
       this._client,
@@ -539,7 +540,8 @@ export class NetworkManager extends EventEmitter {
     const interceptionId = request._interceptionId;
 
     this._networkEventManager.forgetRequest(requestId);
-    this._attemptedAuthentications.delete(interceptionId);
+    interceptionId !== undefined &&
+      this._attemptedAuthentications.delete(interceptionId);
 
     if (events) {
       this._networkEventManager.forget(requestId);
@@ -567,7 +569,7 @@ export class NetworkManager extends EventEmitter {
 
     // Under certain conditions we never get the Network.responseReceived
     // event from protocol. @see https://crbug.com/883475
-    if (request.response()) request.response()._resolveBody(null);
+    if (request.response()) request.response()?._resolveBody(null);
     this._forgetRequest(request, true);
     this.emit(NetworkManagerEmittedEvents.RequestFinished, request);
   }