Fix: miscellaneous not initialized vars

htdocs/compta/facture.php

htdocs/compta/facture/class/facture.class.php

htdocs/compta/paiement/fiche.php

htdocs/compta/payment_sc/fiche.php

htdocs/core/class/commonobject.class.php

htdocs/core/lib/functions.lib.php

htdocs/core/modules/cheque/pdf/modules_chequereceipts.php

htdocs/core/modules/commande/modules_commande.php

htdocs/core/modules/facture/modules_facture.php

htdocs/core/modules/modWorkflow.class.php

htdocs/core/modules/propale/modules_propale.php

...core/modules/supplier_invoice/pdf/pdf_canelle.modules.php

scripts/invoices/rebuild_merge_pdf.php

test/phpunit/BuildDocTest.php