FontDescription.LoadDescription throws ArgumentException

[Metalnem]

FontDescription.LoadDescription throws an ArgumentException when loading the font from the attached archive. You can run the following code to reproduce it (the path variable should contain the path to the extracted file):

FontDescription.LoadDescription(path);

Found via SharpFuzz.

[dlemstra]

The full exception is:

System.ArgumentException : An item with the same key has already been added. Key: kern
Stack Trace:
  at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
  at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
  at SixLabors.Fonts.FontReader..ctor(Stream stream, TableLoader loader)
  at SixLabors.Fonts.FontReader..ctor(Stream stream)
  at SixLabors.Fonts.FontDescription.LoadDescription(String path)

Okay if I add a patch that does headers[tbl.Tag] instead of headers.Add(tbl.Tag) @tocsoft?

[tocsoft]

no real problem, not sure its a valid font file with duplicate tables but preventing it breaking with an unhelpful error is better

[Metalnem]

Not a valid font - it was obtained by fuzzing the library. The fuzzer started with a small valid font and generated thousands of random mutations before generating this particular one.

[dlemstra]

@tocsoft What would you prefer that we do if we find a duplicate table? Don't understand your answer 😉

[tocsoft]

Just replace the previous entry for now like you suggested. We can worry about correctness later as I can't currently find anything saying it's invalid to have duplicate tables defined.