Related discussions

• What's the proper usage of snippet nested placeholders? neovim/neovim#36232

${1:another ${2:placeholder}} (a snippet example provided here) isn't a valid snippet according to the LSP grammar.

A placeholder node is defined as placeholder ::= '${' int ':' any '}' where any ::= tabstop | placeholder | choice | variable | text. In the provided snippet the any (after the colon) would match another (as a text node) and then parsing crashes (as expected) because the placeholder value incorrectly consists of multiple nodes.

In order to ensure consistency across editors (as a primary goal of LSP) we need to clarify the feature descriptions and/or grammar to reflect the expected capabilities.