This error is usually caused by an incomplete, incompatible or corrupt font. To test if a corupted font is causing this error, from Preferences > Type then disable Font Preview. If typing works now, then a font the issue. If you are on Windows, uninstall and then reinstall your most recent fonts. The files will be verified when reinstalled and most probably one or more might give som error.
If you are on Mac, use Fontbook to validate your fonts.