Do not create PdfFileReader with empty data

pyPdf goes in an infinite loop when PdfFileReader are created on an empty file.

bt5/erp5_pdf_merge/ExtensionTemplateItem/ERP5PDFMerge.py

@@ -41,6 +41,7 @@ def mergePDFList(self, pdf_data_list, start_on_recto=False):
   output = PdfFileWriter()
   
   for pdf_data in pdf_data_list:
+    if pdf_data:
       pdf_reader = PdfFileReader(StringIO(pdf_data))
       page_count = pdf_reader.getNumPages()
       for page in range(page_count):

bt5/erp5_pdf_merge/bt/revision

-1
+2
\ No newline at end of file

product/ERP5/Document/PDFDocument.py

@@ -83,6 +83,10 @@ class PDFDocument(Image):
       index is 0 based)
     """
     from pyPdf import PdfFileWriter, PdfFileReader, pdf
+    if not watermark_data:
+      raise ValueError("watermark_data cannot not be empty")
+    if not self.hasData():
+      raise ValueError("Cannot watermark an empty document")
     self_reader = PdfFileReader(StringIO(self.getData()))
     watermark_reader = PdfFileReader(StringIO(watermark_data))
     watermark_page_count = watermark_reader.getNumPages()