In the OP_Column opcode, when extracting a field that is past the end of

a short record (because the row was originally inserted prior to ALTER TABLE
ADD COLUMN) then make sure the output register is fully NULL and does not
contain leftover flags (such as MEM_Ephem) from its previous use.
Fix for ticket [43107840f1c02].  This is a cherrypick of
check-in [24780f8ddc1683fc].

FossilOrigin-Name: 304ea6ba6f4cf40a76d32d37af73a253f493ba47

src/vdbe.c

@@ -2441,7 +2441,7 @@ case OP_Column: {
       if( pOp->p4type==P4_MEM ){
         sqlite3VdbeMemShallowCopy(pDest, pOp->p4.pMem, MEM_Static);
       }else{
-        MemSetTypeFlag(pDest, MEM_Null);
+        sqlite3VdbeMemSetNull(pDest);
       }
       goto op_column_out;
     }