These could be the result of not activating the MI mode in lldb-mi,
because of the previous error message. How about asking the lldb-mi
maintainers what should be the correct invocation of this tool?
Thanks.
The subset of MI commands that lldb-mi currently understands is very narrow and was added to support one specific consumer (I think it might have been Eclipse, but I could be misremembering). In any case, it looks like lldb-mi is missing the implementation for certain MI commands that Emacs is expecting. Adding these shouldn't be too much work if you're building on top of the LLDB scripting API.