Handle null token in DirectObjectFinder, handle null state in SetName…

…dGraphicsState(), add and test and fix UglyToad#874

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

@@ -0,0 +1,26 @@
+namespace UglyToad.PdfPig.Tests.Integration
+{
+    public class GithubIssuesTests
+    {
+        [Fact]
+        public void Issue874()
+        {
+            var doc = IntegrationHelpers.GetDocumentPath("ErcotFacts.pdf");
+
+            using (var document = PdfDocument.Open(doc, new ParsingOptions() { UseLenientParsing = true, SkipMissingFonts = true }))
+            {
+                var page1 = document.GetPage(1);
+                Assert.Equal(1788, page1.Letters.Count);
+
+                var page2 = document.GetPage(2);
+                Assert.Equal(2430, page2.Letters.Count);
+            }
+
+            using (var document = PdfDocument.Open(doc, new ParsingOptions() { UseLenientParsing = true, SkipMissingFonts = false }))
+            {
+                var ex = Assert.Throws<ArgumentNullException>(() => document.GetPage(1));
+                Assert.StartsWith("Value cannot be null.", ex.Message);
+            }
+        }
+    }
+}

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

@@ -6,7 +6,8 @@ public class IntegrationDocumentTests
         private static readonly HashSet<string> _documentsToIgnore =
         [
             "issue_671.pdf",
-            "GHOSTSCRIPT-698363-0.pdf"
+            "GHOSTSCRIPT-698363-0.pdf",
+            "ErcotFacts.pdf"
         ];
 
         [Theory]

src/UglyToad.PdfPig/Graphics/BaseStreamProcessor.cs

@@ -665,6 +665,11 @@ public virtual void SetNamedGraphicsState(NameToken stateName)
 
             var state = ResourceStore.GetExtendedGraphicsStateDictionary(stateName);
 
+            if (state is null)
+            {
+                return;
+            }
+
             if (state.TryGet(NameToken.Lw, PdfScanner, out NumericToken? lwToken))
             {
                 currentGraphicsState.LineWidth = lwToken.Data;

src/UglyToad.PdfPig/Parser/Parts/DirectObjectFinder.cs

@@ -32,6 +32,11 @@ public static bool TryGet<T>(IToken? token, IPdfTokenScanner scanner, [NotNullWh
             {
                 var temp = scanner.Get(reference.Data);
 
+                if (temp is null)
+                {
+                    return false;
+                }
+
                 if (temp.Data is T tTemp)
                 {
                     tokenResult = tTemp;