Enable the unicorn/prefer-optional-catch-binding ESLint plugin rule

According to MDN this format is available in all browsers/environments that we currently support, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/try...catch#browser_compatibility

Please also see https://github.com/sindresorhus/eslint-plugin-unicorn/blob/main/docs/rules/prefer-optional-catch-binding.md

web/app.js

@@ -815,7 +815,7 @@ const PDFViewerApplication = {
     if (!title) {
       try {
         title = decodeURIComponent(getFilenameFromUrl(url)) || url;
-      } catch (ex) {
+      } catch {
         // decodeURIComponent may throw URIError,
         // fall back to using the unprocessed url in that case
         title = url;
@@ -876,7 +876,7 @@ const PDFViewerApplication = {
       try {
         // Trigger saving, to prevent data loss in forms; see issue 12257.
         await this.save();
-      } catch (reason) {
+      } catch {
         // Ignoring errors, to ensure that document closing won't break.
       }
     }
@@ -1044,7 +1044,7 @@ const PDFViewerApplication = {
       const blob = new Blob([data], { type: "application/pdf" });
 
       await this.downloadManager.download(blob, url, filename, options);
-    } catch (reason) {
+    } catch {
       // When the PDF document isn't ready, or the PDF file is still
       // downloading, simply download using the URL.
       await this.downloadManager.downloadUrl(url, filename, options);

web/chromecom.js

@@ -150,7 +150,7 @@ function isRuntimeAvailable() {
     if (chrome.runtime?.getManifest()) {
       return true;
     }
-  } catch (e) {}
+  } catch {}
   return false;
 }
 

web/grab_to_pan.js

@@ -106,7 +106,7 @@ class GrabToPan {
       try {
         // eslint-disable-next-line no-unused-expressions
         event.originalTarget.tagName;
-      } catch (e) {
+      } catch {
         // Mozilla-specific: element is a scrollbar (XUL element)
         return;
       }

web/pdf_link_service.js

@@ -445,7 +445,7 @@ class PDFLinkService {
           // e.g. "4.3" or "true", because `JSON.parse` converted its type.
           dest = dest.toString();
         }
-      } catch (ex) {}
+      } catch {}
 
       if (
         typeof dest === "string" ||

web/pdf_outline_viewer.js

@@ -341,7 +341,7 @@ class PDFOutlineViewer extends BaseTreeViewer {
                   return null; // The document was closed while the data resolved.
                 }
                 this.linkService.cachePageRef(pageNumber, destRef);
-              } catch (ex) {
+              } catch {
                 // Invalid page reference, ignore it and continue parsing.
               }
             }

web/pdf_presentation_mode.js

@@ -101,7 +101,7 @@ class PDFPresentationMode {
       await promise;
       pdfViewer.focus(); // Fixes bug 1787456.
       return true;
-    } catch (reason) {
+    } catch {
       this.#removeFullscreenChangeListeners();
       this.#notifyStateChange(PresentationModeState.NORMAL);
     }

web/pdf_scripting_manager.js

@@ -487,7 +487,7 @@ class PDFScriptingManager {
 
     try {
       await this._scripting.destroySandbox();
-    } catch (ex) {}
+    } catch {}
 
     for (const [name, listener] of this._internalEvents) {
       this._eventBus._off(name, listener);