Apply more strict typescript around the codebase (#2778)

* Apply more strict typescript around the codebase

* Fix tests

* Revert strict mode commit

* Iterate strict

* Iterate

* Iterate strict

* Iterate

* Fix tests

* Iterate

* Iterate strict

* Add tests

* Iterate

* Iterate

* Fix tests

* Fix tests

* Strict types be strict

* Fix types

* detectOpenHandles

* Strict

* Fix client not stopping

* Add sync peeking tests

* Make test happier

* More strict

* Iterate

* Stabilise

* Moar strictness

* Improve coverage

* Fix types

* Fix types

* Improve types further

* Fix types

* Improve typing of NamespacedValue

* Fix types

src/http-api/errors.ts

@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 import { IUsageLimit } from "../@types/partials";
+import { MatrixEvent } from "../models/event";
 
 interface IErrorJson extends Partial<IUsageLimit> {
     [key: string]: any; // extensible
@@ -50,7 +51,12 @@ export class MatrixError extends HTTPError {
     public readonly errcode?: string;
     public readonly data: IErrorJson;
 
-    constructor(errorJson: IErrorJson = {}, public readonly httpStatus?: number, public url?: string) {
+    constructor(
+        errorJson: IErrorJson = {},
+        public readonly httpStatus?: number,
+        public url?: string,
+        public event?: MatrixEvent,
+    ) {
         let message = errorJson.error || "Unknown message";
         if (httpStatus) {
             message = `[${httpStatus}] ${message}`;

src/http-api/fetch.ts

@@ -73,7 +73,7 @@ export class FetchHttpApi<O extends IHttpOpts> {
     public idServerRequest<T extends {}>(
         method: Method,
         path: string,
-        params: Record<string, string | string[]>,
+        params: Record<string, string | string[]> | undefined,
         prefix: string,
         accessToken?: string,
     ): Promise<ResponseType<T, O>> {
@@ -96,7 +96,7 @@ export class FetchHttpApi<O extends IHttpOpts> {
             headers: {},
         };
         if (accessToken) {
-            opts.headers.Authorization = `Bearer ${accessToken}`;
+            opts.headers!.Authorization = `Bearer ${accessToken}`;
         }
 
         return this.requestOtherUrl(method, fullUri, body, opts);
@@ -286,10 +286,10 @@ export class FetchHttpApi<O extends IHttpOpts> {
                 credentials: "omit", // we send credentials via headers
             });
         } catch (e) {
-            if (e.name === "AbortError") {
+            if ((<Error>e).name === "AbortError") {
                 throw e;
             }
-            throw new ConnectionError("fetch failed", e);
+            throw new ConnectionError("fetch failed", <Error>e);
         } finally {
             cleanup();
         }

src/http-api/utils.ts

@@ -72,11 +72,11 @@ export function anySignal(signals: AbortSignal[]): {
  * @returns {Error}
  */
 export function parseErrorResponse(response: XMLHttpRequest | Response, body?: string): Error {
-    let contentType: ParsedMediaType;
+    let contentType: ParsedMediaType | null;
     try {
         contentType = getResponseContentType(response);
     } catch (e) {
-        return e;
+        return <Error>e;
     }
 
     if (contentType?.type === "application/json" && body) {