Bug #9121 for DBD-SQLite: Spurious "use of uninitialised value in subroutine" with ->execute()

Use of uninitialized value in subroutine entry at lib/Tangram/Storage.pm line 672, <CONFIG> line 1. Use of uninitialized value in subroutine entry at lib/Tangram/Storage.pm line 672, <CONFIG> line 1. Use of uninitialized value in subroutine entry at lib/Tangram/Storage.pm line 672, <CONFIG> line 1. Use of uninitialized value in subroutine entry at lib/Tangram/Storage.pm line 672, <CONFIG> line 1. Use of uninitialized value in subroutine entry at lib/Tangram/Storage.pm line 672, <CONFIG> line 1. Use of uninitialized value in subroutine entry at lib/Tangram/Storage.pm line 672, <CONFIG> line 1. Use of uninitialized value in subroutine entry at lib/Tangram/Storage.pm line 672, <CONFIG> line 1. Use of uninitialized value in subroutine entry at lib/Tangram/Storage.pm line 672, <CONFIG> line 1. Use of uninitialized value in subroutine entry at lib/Tangram/Storage.pm line 672, <CONFIG> line 1. Use of uninitialized value in subroutine entry at lib/Tangram/Storage.pm line 672, <CONFIG> line 1. tracked it down to a trace message that was calling SvPV_nolen on a string before checking it was SvPOK. See attached patch.