diff --git a/src/display/api.js b/src/display/api.js
index 43954cabd..3b1ca159c 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -229,7 +229,7 @@ const DefaultStandardFontDataFactory =
  *         already populated with data, or a parameter object.
  * @returns {PDFDocumentLoadingTask}
  */
-function getDocument(src) {
+function getDocument(src = {}) {
   if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
     if (typeof src === "string" || src instanceof URL) {
       src = { url: src };
@@ -237,14 +237,6 @@ function getDocument(src) {
       src = { data: src };
     }
   }
-  if (typeof src !== "object") {
-    throw new Error("Invalid parameter in getDocument, need parameter object.");
-  }
-  if (!src.url && !src.data && !src.range) {
-    throw new Error(
-      "Invalid parameter object: need either .data, .range or .url"
-    );
-  }
   const task = new PDFDocumentLoadingTask();
   const { docId } = task;
 
@@ -423,6 +415,9 @@ function getDocument(src) {
         if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
           throw new Error("Not implemented: createPDFNetworkStream");
         }
+        if (!url) {
+          throw new Error("getDocument - no `url` parameter provided.");
+        }
         const createPDFNetworkStream = params => {
           if (
             typeof PDFJSDev !== "undefined" &&
@@ -2091,6 +2086,14 @@ class PDFWorker {
     return this._readyCapability.promise;
   }
 
+  #resolve() {
+    this._readyCapability.resolve();
+    // Send global setting, e.g. verbosity level.
+    this._messageHandler.send("configure", {
+      verbosity: this.verbosity,
+    });
+  }
+
   /**
    * The current `workerPort`, when it exists.
    * @type {Worker}
@@ -2117,11 +2120,7 @@ class PDFWorker {
       // Ignoring "ready" event -- MessageHandler should already be initialized
       // and ready to accept messages.
     });
-    this._readyCapability.resolve();
-    // Send global setting, e.g. verbosity level.
-    this._messageHandler.send("configure", {
-      verbosity: this.verbosity,
-    });
+    this.#resolve();
   }
 
   _initialize() {
@@ -2129,103 +2128,99 @@ class PDFWorker {
     // support, create a new web worker and test if it/the browser fulfills
     // all requirements to run parts of pdf.js in a web worker.
     // Right now, the requirement is, that an Uint8Array is still an
-    // Uint8Array as it arrives on the worker. (Chrome added this with v.15.)
+    // Uint8Array as it arrives on the worker.
     if (
-      !PDFWorkerUtil.isWorkerDisabled &&
-      !PDFWorker.#mainThreadWorkerMessageHandler
+      PDFWorkerUtil.isWorkerDisabled ||
+      PDFWorker.#mainThreadWorkerMessageHandler
     ) {
-      let { workerSrc } = PDFWorker;
+      this._setupFakeWorker();
+      return;
+    }
+    let { workerSrc } = PDFWorker;
 
-      try {
-        // Wraps workerSrc path into blob URL, if the former does not belong
-        // to the same origin.
-        if (
-          typeof PDFJSDev !== "undefined" &&
-          PDFJSDev.test("GENERIC") &&
-          !PDFWorkerUtil.isSameOrigin(window.location.href, workerSrc)
-        ) {
-          workerSrc = PDFWorkerUtil.createCDNWrapper(
-            new URL(workerSrc, window.location).href
-          );
+    try {
+      // Wraps workerSrc path into blob URL, if the former does not belong
+      // to the same origin.
+      if (
+        typeof PDFJSDev !== "undefined" &&
+        PDFJSDev.test("GENERIC") &&
+        !PDFWorkerUtil.isSameOrigin(window.location.href, workerSrc)
+      ) {
+        workerSrc = PDFWorkerUtil.createCDNWrapper(
+          new URL(workerSrc, window.location).href
+        );
+      }
+
+      const worker = new Worker(workerSrc, { type: "module" });
+      const messageHandler = new MessageHandler("main", "worker", worker);
+      const terminateEarly = () => {
+        ac.abort();
+        messageHandler.destroy();
+        worker.terminate();
+        if (this.destroyed) {
+          this._readyCapability.reject(new Error("Worker was destroyed"));
+        } else {
+          // Fall back to fake worker if the termination is caused by an
+          // error (e.g. NetworkError / SecurityError).
+          this._setupFakeWorker();
         }
+      };
 
-        const worker = new Worker(workerSrc, { type: "module" });
-        const messageHandler = new MessageHandler("main", "worker", worker);
-        const terminateEarly = () => {
-          worker.removeEventListener("error", onWorkerError);
-          messageHandler.destroy();
-          worker.terminate();
-          if (this.destroyed) {
-            this._readyCapability.reject(new Error("Worker was destroyed"));
-          } else {
-            // Fall back to fake worker if the termination is caused by an
-            // error (e.g. NetworkError / SecurityError).
-            this._setupFakeWorker();
-          }
-        };
-
-        const onWorkerError = () => {
+      const ac = new AbortController();
+      worker.addEventListener(
+        "error",
+        () => {
           if (!this._webWorker) {
             // Worker failed to initialize due to an error. Clean up and fall
             // back to the fake worker.
             terminateEarly();
           }
-        };
-        worker.addEventListener("error", onWorkerError);
+        },
+        { signal: ac.signal }
+      );
 
-        messageHandler.on("test", data => {
-          worker.removeEventListener("error", onWorkerError);
-          if (this.destroyed) {
-            terminateEarly();
-            return; // worker was destroyed
-          }
-          if (data) {
-            this._messageHandler = messageHandler;
-            this._port = worker;
-            this._webWorker = worker;
+      messageHandler.on("test", data => {
+        ac.abort();
+        if (this.destroyed || !data) {
+          terminateEarly();
+          return;
+        }
+        this._messageHandler = messageHandler;
+        this._port = worker;
+        this._webWorker = worker;
 
-            this._readyCapability.resolve();
-            // Send global setting, e.g. verbosity level.
-            messageHandler.send("configure", {
-              verbosity: this.verbosity,
-            });
-          } else {
-            this._setupFakeWorker();
-            messageHandler.destroy();
-            worker.terminate();
-          }
-        });
+        this.#resolve();
+      });
 
-        messageHandler.on("ready", data => {
-          worker.removeEventListener("error", onWorkerError);
-          if (this.destroyed) {
-            terminateEarly();
-            return; // worker was destroyed
-          }
-          try {
-            sendTest();
-          } catch {
-            // We need fallback to a faked worker.
-            this._setupFakeWorker();
-          }
-        });
+      messageHandler.on("ready", data => {
+        ac.abort();
+        if (this.destroyed) {
+          terminateEarly();
+          return;
+        }
+        try {
+          sendTest();
+        } catch {
+          // We need fallback to a faked worker.
+          this._setupFakeWorker();
+        }
+      });
 
-        const sendTest = () => {
-          const testObj = new Uint8Array();
-          // Ensure that we can use `postMessage` transfers.
-          messageHandler.send("test", testObj, [testObj.buffer]);
-        };
+      const sendTest = () => {
+        const testObj = new Uint8Array();
+        // Ensure that we can use `postMessage` transfers.
+        messageHandler.send("test", testObj, [testObj.buffer]);
+      };
 
-        // It might take time for the worker to initialize. We will try to send
-        // the "test" message immediately, and once the "ready" message arrives.
-        // The worker shall process only the first received "test" message.
-        sendTest();
-        return;
-      } catch {
-        info("The worker has been disabled.");
-      }
+      // It might take time for the worker to initialize. We will try to send
+      // the "test" message immediately, and once the "ready" message arrives.
+      // The worker shall process only the first received "test" message.
+      sendTest();
+      return;
+    } catch {
+      info("The worker has been disabled.");
     }
-    // Either workers are disabled, not supported or have thrown an exception.
+    // Either workers are not supported or have thrown an exception.
     // Thus, we fallback to a faked worker.
     this._setupFakeWorker();
   }
@@ -2253,13 +2248,8 @@ class PDFWorker {
         const workerHandler = new MessageHandler(id + "_worker", id, port);
         WorkerMessageHandler.setup(workerHandler, port);
 
-        const messageHandler = new MessageHandler(id, id + "_worker", port);
-        this._messageHandler = messageHandler;
-        this._readyCapability.resolve();
-        // Send global setting, e.g. verbosity level.
-        messageHandler.send("configure", {
-          verbosity: this.verbosity,
-        });
+        this._messageHandler = new MessageHandler(id, id + "_worker", port);
+        this.#resolve();
       })
       .catch(reason => {
         this._readyCapability.reject(