Problem

Sentry reported an IllegalStateException: Already closed crash in the PDF viewer on Android (Sentry issue).

The crash originates from io.legere.pdfiumandroid.util.ConfigKt.handleAlreadyClosed when the native PdfiumAndroid rendering thread tries to render a page bitmap after the PDF document has already been closed.

Root cause: When switching between single-page and continuous view modes, the Pdf component uses key={viewMode} which causes React to unmount the old instance and mount a new one synchronously. During unmount, the native PDF document is closed, but the background RenderingHandler thread may still be mid-render, leading to the Already closed exception.

Fix

• Added a pdfMounted state that explicitly unmounts the Pdf component before changing the view mode
• The component is remounted on the next animation frame via requestAnimationFrame, giving the native rendering thread time to finish before document resources are released
• The key={viewMode} is preserved so React still creates a fresh instance with the new configuration

Stack trace

IllegalStateException: Already closed
  RenderingHandler.handleMessage → RenderingHandler.proceed → PdfFile.renderPageBitmap
  → PdfiumCore.renderPageBitmap → PdfPage.renderPageBitmap → PdfPage.close
  → ConfigKt.handleAlreadyClosed