refactor: btns fallback

src/btn.ts

@@ -160,19 +160,13 @@ export namespace BtnAction {
     })
   }
 
-  export const download = (url: UrlInput, fallback?: () => Promisable<void>, timeout = Infinity): BtnAction => {
+  export const download = (url: UrlInput, fallback?: () => Promisable<void>, timeout?: number): BtnAction => {
     return process(async (): Promise<void> => {
-      try {
-        const _url = await useTimeout(normalizeUrlInput(url), timeout)
-        const a = document.createElement('a')
-        a.href = _url
-        a.dispatchEvent(new MouseEvent('click'))
-      } catch (err) {
-        // use fallback
-        console.error(err)
-        return fallback?.()
-      }
-    })
+      const _url = await normalizeUrlInput(url)
+      const a = document.createElement('a')
+      a.href = _url
+      a.dispatchEvent(new MouseEvent('click'))
+    }, fallback, timeout)
   }
 
   export const mscoreWindow = (fn: (w: Window, score: WebMscore, processingTextEl: ChildNode) => any): BtnAction => {
@@ -206,7 +200,7 @@ export namespace BtnAction {
     }
   }
 
-  export const process = (fn: () => any): BtnAction => {
+  export const process = (fn: () => any, fallback?: () => Promisable<void>, timeout = Infinity): BtnAction => {
     return async (name, btn, setText): Promise<void> => {
       const _onclick = btn.onclick
 
@@ -214,11 +208,17 @@ export namespace BtnAction {
       setText(i18n('PROCESSING')())
 
       try {
-        await fn()
+        await useTimeout(fn(), timeout)
         setText(name)
       } catch (err) {
-        setText(i18n('BTN_ERROR')())
         console.error(err)
+        if (fallback) {
+          // use fallback
+          await fallback()
+          setText(name)
+        } else {
+          setText(i18n('BTN_ERROR')())
+        }
       }
 
       btn.onclick = _onclick

src/main.ts

@@ -14,7 +14,6 @@ const main = (): void => {
   const filename = scoreinfo.fileName
 
   let indvPartBtn: HTMLButtonElement | null = null
-  const timeout = 30 * 1000 // 30s
   const fallback = () => {
     // btns fallback to load from MSCZ file (`Individual Parts`)
     return indvPartBtn?.click()
@@ -27,7 +26,7 @@ const main = (): void => {
 
   btnList.add({
     name: i18n('DOWNLOAD')('PDF'),
-    action: BtnAction.process(downloadPDF),
+    action: BtnAction.process(downloadPDF, fallback, 3 * 60 * 1000 /* 3min */),
   })
 
   btnList.add({
@@ -42,12 +41,12 @@ const main = (): void => {
 
   btnList.add({
     name: i18n('DOWNLOAD')('MIDI'),
-    action: BtnAction.download(() => getFileUrl('midi'), fallback, timeout),
+    action: BtnAction.download(() => getFileUrl('midi'), fallback, 30 * 1000 /* 30s */),
   })
 
   btnList.add({
     name: i18n('DOWNLOAD')('MP3'),
-    action: BtnAction.download(() => getFileUrl('mp3'), fallback, timeout),
+    action: BtnAction.download(() => getFileUrl('mp3'), fallback, 30 * 1000 /* 30s */),
   })
 
   indvPartBtn = btnList.add({