Fix exception in error logging in ineptpdf

DeDRM_plugin/ineptpdf.py

@@ -1636,13 +1636,15 @@ class PDFDocument(object):
             else:
                 print("ebx_V is %d  and ebx_type is %d" % (ebx_V, ebx_type))
                 print("length is %d and len(bookkey) is %d" % (length, len(bookkey)))
-                print("bookkey[0] is %d" % bookkey[0])
+                if len(bookkey) > 0:
+                    print("bookkey[0] is %d" % bookkey[0])
                 raise ADEPTError('error decrypting book session key - mismatched length')
         else:
             # proper length unknown try with whatever you have
             print("ebx_V is %d  and ebx_type is %d" % (ebx_V, ebx_type))
             print("length is %d and len(bookkey) is %d" % (length, len(bookkey)))
-            print("bookkey[0] is %d" % ord(bookkey[0]))
+            if len(bookkey) > 0:
+                print("bookkey[0] is %d" % ord(bookkey[0]))
             if ebx_V == 3:
                 V = 3
             else:
@@ -1708,13 +1710,15 @@ class PDFDocument(object):
             else:
                 print("ebx_V is %d  and ebx_type is %d" % (ebx_V, ebx_type))
                 print("length is %d and len(bookkey) is %d" % (length, len(bookkey)))
-                print("bookkey[0] is %d" % bookkey[0])
+                if len(bookkey) > 0:
+                    print("bookkey[0] is %d" % bookkey[0])
                 raise ADEPTError('error decrypting book session key - mismatched length')
         else:
             # proper length unknown try with whatever you have
             print("ebx_V is %d  and ebx_type is %d" % (ebx_V, ebx_type))
             print("length is %d and len(bookkey) is %d" % (length, len(bookkey)))
-            print("bookkey[0] is %d" % bookkey[0])
+            if len(bookkey) > 0:
+                print("bookkey[0] is %d" % bookkey[0])
             if ebx_V == 3:
                 V = 3
             else: