They are already quoted so they mean ''Metals-light and ''Metals-dark. It is wrong.
Development Emacs warns this as byte-compile warnings as below.
lsp-metals-treeview.el:82:12: Warning: defcustom for
‘lsp-metals-treeview-theme’ has syntactically odd type ‘'(choice (const
:tag Light 'Metals-light) (const :tag Dark 'Metals-dark))’
They are already quoted so they mean
''Metals-light
and''Metals-dark
. It is wrong.Development Emacs warns this as byte-compile warnings as below.