Fix value error and key error

CHANGELOG.md

@@ -7,6 +7,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## [Unreleased]
 
 ### Fixed
+- Fix issue of ValueError and KeyError rasied in PDFdocument and PDFparser ([#573](https://github.com/pdfminer/pdfminer.six/pull/574))
 - Fix issue of TypeError: cannot unpack non-iterable PDFObjRef object, when unpacking the value of 'DW2' ([#529](https://github.com/pdfminer/pdfminer.six/pull/529))
 - `PermissionError` when creating temporary filepaths on windows when running tests ([#469](https://github.com/pdfminer/pdfminer.six/issues/469))
 

pdfminer/pdfdocument.py

@@ -230,7 +230,7 @@ def load(self, parser):
         (_, kwd) = parser.nexttoken()
         (_, stream) = parser.nextobject()
         if not isinstance(stream, PDFStream) \
-                or stream['Type'] is not LITERAL_XREF:
+                or stream.get('Type') is not LITERAL_XREF:
             raise PDFNoValidXRef('Invalid PDF stream spec.')
         size = stream['Size']
         index_array = stream.get('Index', (0, size))

pdfminer/pdfparser.py

@@ -68,14 +68,14 @@ def do_keyword(self, pos, token):
 
         elif token is self.KEYWORD_R:
             # reference to indirect object
-            try:
-                ((_, objid), (_, genno)) = self.pop(2)
-                (objid, genno) = (int(objid), int(genno))
-                obj = PDFObjRef(self.doc, objid, genno)
-                self.push((pos, obj))
-            except PSSyntaxError:
-                pass
-
+            if len(self.curstack) >= 2:
+                try:
+                    ((_, objid), (_, genno)) = self.pop(2)
+                    (objid, genno) = (int(objid), int(genno))
+                    obj = PDFObjRef(self.doc, objid, genno)
+                    self.push((pos, obj))
+                except PSSyntaxError:
+                    pass
         elif token is self.KEYWORD_STREAM:
             # stream object
             ((_, dic),) = self.pop(1)