handle unexpected adobe type 1 format

an encoding array in an adobe type 1 font may be missing its declaration ending in 'for', if we encounter 'dup' while looking for the 'for' token we have a special case to go straight into reading the encoding.

also handles a case where the page content stream contains a path-closing operator without any path being active.

src/UglyToad.PdfPig/Graphics/ContentStreamProcessor.cs

@@ -413,6 +413,11 @@
 
         public void StrokePath(bool close)
         {
+            if (CurrentPath == null)
+            {
+                return;
+            }
+
             if (close)
             {
                 ClosePath();
@@ -427,6 +432,11 @@
 
         public void FillPath(bool close)
         {
+            if (CurrentPath == null)
+            {
+                return;
+            }
+
             if (close)
             {
                 ClosePath();