^ lib/theme/jam_icons icons.dart:78:70: Context: Expected constant 'null' to be of type 'String', but was of type 'Null'. IconData(0xe922, fontFamily: _kFontFam, font Package: _kFont Pkg as String); ^ how to solve it code example

Example: ^ lib/theme/jam_icons icons.dart:78:70: Context: Expected constant 'null' to be of type 'String', but was of type 'Null'. IconData(0xe922, fontFamily: _kFontFam, font Package: _kFont Pkg as String); ^ how to solve it

how to solve this error