Prevent tree-sitter error on buffers that don't yet have a filetype

[dansalvato]

Some debug adapters occasionally create a stack frame in a brand new buffer, e.g. if jumping into memory that requires disassembly. For some reason, there are rare cases where nvim-dap fires listener events on the new frame before Neovim has had the chance to determine the filetype. Since the filetype is empty, tree-sitter throws an error on get_parser().

This fix manually calls vim.filetype.match() on the buffer if the filetype is empty. If still empty, the function exits early.

So, this fixes the rare edge case I was experiencing, as well as any potential case where Neovim cannot determine the filetype of the file being stepped into.

[theHamsta]

Looks good to me! Thank you!