GetGlyphIndex sets a dictionary value and can fail

[charlesroddie]

A GetGlyphIndex method is internally trying to set something. This can result in errors like:

Dictionary`2[TKey,TValue].TryInsert (TKey key, TValue value, System.Collections.Generic.InsertionBehavior behavior)
SIGABRT: Operations that change non-concurrent collections must have exclusive access. A concurrent update was performed on this collection and corrupted its state. The collection's state is no longer correct.

Dictionary`2[TKey,TValue].TryInsert (TKey key, TValue value, System.Collections.Generic.InsertionBehavior behavior)
Dictionary`2[TKey,TValue].set_Item (TKey key, TValue value)
Cmap.GetGlyphIndex (System.Int32 codepoint, System.Int32 nextCodepoint, System.Boolean& skipNextCodepoint)
Typeface.GetGlyphIndex (System.Int32 codepoint)
GlyphFinder.Lookup (CSharpMath.Rendering.BackEnd.Fonts fonts, System.Int32 codepoint)