Please help us to fix it by copying the following text and pasting it into a new post on https://forum.glyphsapp.com. Thanks!
text: '' (__NSCFString), length: 0, string: 'É{
}' (NSConcreteAttributedString), length: 1, range: {0, 1}
NSInvalidArgumentException
-[__NSCFString replaceCharactersInRange:withString:]: Range or index out of bounds
(
"3 CoreFoundation 0x000000018f572b2c mutateError2 + 0",
"4 CoreFoundation 0x000000018f4183f8 CFStringCreateFromExternalRepresentation + 0",
"5 Foundation 0x0000000190c7fbb8 -[NSConcreteMutableAttributedString replaceCharactersInRange:withAttributedString:\] + 220",
"6 GlyphsApp 0x0000000104b10aac -[GSGlyphEditView(NSText) doInsertText:replacementRange:] + 796",
"7 GlyphsApp 0x0000000104b10760 -[GSGlyphEditView(NSText) insertText:replacementRange:] + 256",
"8 AppKit 0x0000000194051164 +[NSInputAnalytics(TrackedActionsManager) allowActionTrackingAnalyticsWithName:forAction:] + 160",
"9 AppKit 0x00000001939d6f0c -[NSTextInputContext(NSInputContext_WithCompletion) insertText:replacementRange:completionHandler:] + 224"
)