skip invalid commands in type 1 command definitions

src/UglyToad.PdfPig/Fonts/Type1/CharStrings/Type1CharStringParser.cs

@@ -83,7 +83,8 @@
 
                     if (command == null)
                     {
-                        throw new InvalidOperationException($"Could not find command with code {b}.");
+                        // Treat as invalid but skip
+                        continue;
                     }
 
                     interpreted.Add(new Union<decimal, LazyType1Command>.Case2(command));

src/UglyToad.PdfPig/Fonts/Type1/Parser/Type1CharstringDecryptedBytes.cs

@@ -34,5 +34,10 @@
             Subroutine,
             Charstring
         }
+
+        public override string ToString()
+        {
+            return $"{Name} {Source} {Index} {Bytes.Count} bytes";
+        }
     }
 }