Convert the getPdfManager function to be asynchronous

This is fairly old code, and by making the function `async` we can handle initialization errors "automatically" without the need for try-catch statements.

src/core/worker.js

@@ -189,7 +189,7 @@ class WorkerMessageHandler {
       return { numPages, fingerprints, htmlForXfa };
     }
 
-    function getPdfManager({
+    async function getPdfManager({
       data,
       password,
       disableAutoFetch,
@@ -211,32 +211,20 @@ class WorkerMessageHandler {
         password,
         rangeChunkSize,
       };
-      const pdfManagerCapability = Promise.withResolvers();
-      let newPdfManager;
 
       if (data) {
-        try {
+        pdfManagerArgs.source = data;
-          pdfManagerArgs.source = data;
 
-          newPdfManager = new LocalPdfManager(pdfManagerArgs);
+        return new LocalPdfManager(pdfManagerArgs);
-          pdfManagerCapability.resolve(newPdfManager);
-        } catch (ex) {
-          pdfManagerCapability.reject(ex);
-        }
-        return pdfManagerCapability.promise;
       }
+      const pdfStream = new PDFWorkerStream(handler),
+        fullRequest = pdfStream.getFullReader();
 
-      let pdfStream,
+      const pdfManagerCapability = Promise.withResolvers();
+      let newPdfManager,
         cachedChunks = [],
         loaded = 0;
-      try {
-        pdfStream = new PDFWorkerStream(handler);
-      } catch (ex) {
-        pdfManagerCapability.reject(ex);
-        return pdfManagerCapability.promise;
-      }
 
-      const fullRequest = pdfStream.getFullReader();
       fullRequest.headersReady
         .then(function () {
           if (!fullRequest.isRangeSupported) {
@@ -315,7 +303,7 @@ class WorkerMessageHandler {
         cancelXHRs = null;
       });
 
-      cancelXHRs = function (reason) {
+      cancelXHRs = reason => {
         pdfStream.cancelAllRequests(reason);
       };