you step out or step over items that do not have debug enabled source code.
what it means is that you have tried to go too deep ... either you stepped into something like the source code for cout, or a library compiled in release mode with no debug information embedded into it, or something like that.
it is not an error, really, or its a 'user error' ... because the code has no debugging info, it can't show you the source, so it does the next best thing and disassembles it for you. It is unusual to be able to make much sense out of the assembly, and unusual to need to as the code in there is probably established and bug free (we can hope) and the real bug is probably back in your source code (which you have gone past and need to get back to). The only thing the assembly has ever told me was that I messed up a pointer -- it can do that, usually gets so far then gives you one of the address invalid/null/out of bounds/ etc messages.
Not sure what words clion uses but my IDE provides a step-out and that gets me back to my readable code if I accidentally drill into assembly.