Handle SetFlatness operator with no value and fix #682

src/UglyToad.PdfPig.Tests/Integration/GamebookTests.cs

@@ -0,0 +1,19 @@
+namespace UglyToad.PdfPig.Tests.Integration
+{
+    using Xunit;
+
+    public class GamebookTests
+    {
+        [Fact]
+        public void Issue682()
+        {
+            using (var document = PdfDocument.Open(IntegrationHelpers.GetDocumentPath("Gamebook.pdf")))
+            {
+                foreach (var page in document.GetPages())
+                {
+                    Assert.NotNull(page);
+                }
+            }
+        }
+    }
+}

src/UglyToad.PdfPig/Graphics/ReflectionGraphicsStateOperationFactory.cs

@@ -129,6 +129,10 @@ public IGraphicsStateOperation Create(OperatorToken op, IReadOnlyList<IToken> op
                 case SetColorRenderingIntent.Symbol:
                     return new SetColorRenderingIntent((NameToken)operands[0]);
                 case SetFlatnessTolerance.Symbol:
+                    if (operands.Count == 0)
+                    {
+                        return null; // Should not happen by definition
+                    }
                     return new SetFlatnessTolerance(OperandToDecimal(operands[0]));
                 case SetLineCap.Symbol:
                     return new SetLineCap(OperandToInt(operands[0]));