escaping for $ not working

[Konfekt]

For example, when using targets.vim (or user plug-ins providing a i/a$ text-object) with

let g:targets_quotes = '$d'

and using

let g:operator#surround#blocks =\ {
\ '-' : [
\ { 'block' : ['(', ')'], 'motionwise' : ['char', 'line', 'block'], 'keys' : ['(', ')', 'b'] },
\ { 'block' : ['{', '}'], 'motionwise' : ['char', 'line', 'block'], 'keys' : ['{', '}', 'B'] },
\ { 'block' : ["$", "$"], 'motionwise' : ['char','line','block'], 'keys' : ['d'] },
\ ]\ }

then hitting <Plug>(operator-surround-delete)aB when the cursor is between \alpha and \beta on

Yes ${\alpha_\beta{Un^{-1}}^{m}}$ No

produces

Error detected while processing function operator#surround#replace..operator#surround#delete..<SNR>294_delete_surround:
line   31:
E54: Unmatched \(