Every time we are inside a quote block, Elixir is generating the quoted representation of that code block for us. If it finds an inexisting_var variable during this process, Elixir is happy to return its quoted representation, {:inexisting_var, [], Elixir}, on the quoted representation of the code block. However, if we inject this quoted expression on a caller module, we'll get an error because the inexisting_var doesn't exist at all on the context where the generated code will run.
Even if the variable inexisting_var was defined in the caller context, the macro wouldn't be able to access it because we didn't use the var!/1 wrapper around the inexisting_var. If we try to compile the Playground module, we would get a warning ...
