[sqlite] Fix bug in how recover virtual table handles empty.

third_party/sqlite/amalgamation/sqlite3.c

Index: third_party/sqlite/amalgamation/sqlite3.c
diff --git a/third_party/sqlite/amalgamation/sqlite3.c b/third_party/sqlite/amalgamation/sqlite3.c
index 22e11146c99db9946935e7e44a4bb5f3dd9a546e..54d0260bb25bf307c0803e7dcfbaf38c1fc3aa8d 100644
--- a/third_party/sqlite/amalgamation/sqlite3.c
+++ b/third_party/sqlite/amalgamation/sqlite3.c
@@ -137639,6 +137639,7 @@ struct RecoverLeafCursor {
  */
 static int leafCursorLoadPage(RecoverLeafCursor *pCursor, DbPage *pPage){
   const unsigned char *pPageHeader;  /* Header of *pPage */
+  unsigned nCells;                   /* Number of cells in the page */
 
   /* Release the current page. */
   if( pCursor->pPage ){
@@ -137668,10 +137669,17 @@ static int leafCursorLoadPage(RecoverLeafCursor *pCursor, DbPage *pPage){
     return SQLITE_OK;
   }
 
+  /* Leaf contains no data, skip it.  Empty tables, for instance. */
+  nCells = decodeUnsigned16(pPageHeader + kiPageCellCountOffset);;
+  if( nCells<1 ){
+    sqlite3PagerUnref(pPage);
+    return SQLITE_OK;
+  }
+
   /* Take ownership of the page and start decoding. */
   pCursor->pPage = pPage;
   pCursor->iCell = 0;
-  pCursor->nCells = decodeUnsigned16(pPageHeader + kiPageCellCountOffset);
+  pCursor->nCells = nCells;
   return SQLITE_OK;
 }