https://github.com/xfiveco/generator-chisel/blob/master/packages/generator-chisel/lib/commands/create/creators/wp/chisel-starter-theme/Chisel/Extensions/ChiselTwig.php#L60 There is naming conflict here with latest Timber plugin version 1.21.0 Removing this definition and using Timber built in Image worked for me.
https://github.com/xfiveco/generator-chisel/blob/master/packages/generator-chisel/lib/commands/create/creators/wp/chisel-starter-theme/Chisel/Extensions/ChiselTwig.php#L60
There is naming conflict here with latest Timber plugin version 1.21.0
Removing this definition and using Timber built in Image worked for me.