I was getting this error when opening new zshell:

__rvm_cleanse_variables: function definition file not found
command not found: rvm_error

Running the following solved the problem:

rm -f ~/.zcompdump*

Note: The * is incase there are multiple .zcompdump files.

So what goes behind the scenes:

ZSH uses compinit to initialize completion for the current session. To speed up the running of compinit, it can be made to produce a dumped configuration which will be read in on future invocations. This dumped file is .zcompdump in the same directory as the startup files (i.e. $ZDOTDIR or $HOME)