I'm trying to learn vim. When I open the program I'm met with this:
The airline statusline funcref function('airline#extensions#mundo#statusline') has already been added.The airline statusline funcref function('airline#extensions#mundo#statusline') has already been added.
that error message suggests that you have airline installed twice...
did you install airline globally as well as via vundle or something? what does :scriptnames tell you? thanks.
Which was the case for the OP and what looks to be for me too. I ran :scriptnames and got the following references to airline:
56: ~/.vim/bundle/vim-airline/plugin/airline.vim
57: ~/.vim/bundle/vim-airline/autoload/airline.vim
58: ~/.vim/bundle/vim-airline/autoload/airline/init.vim
59: ~/.vim/bundle/vim-airline/autoload/airline/parts.vim
60: ~/.vim/bundle/vim-airline-themes/plugin/airline-themes.vim
78: ~/.vim/bundle/vim-airline/autoload/airline/extensions.vim
79: ~/.vim/bundle/vim-airline/autoload/airline/extensions/quickfix.vim
80: ~/.vim/bundle/vim-airline/autoload/airline/extensions/netrw.vim
81: ~/.vim/bundle/vim-airline/autoload/airline/extensions/ctrlp.vim
82: ~/.vim/bundle/vim-airline/autoload/airline/extensions/commandt.vim
83: ~/.vim/bundle/vim-airline/autoload/airline/extensions/branch.vim
84: ~/.vim/bundle/vim-airline/autoload/airline/extensions/syntastic.vim
85: ~/.vim/bundle/vim-airline/autoload/airline/extensions/whitespace.vim
86: ~/.vim/bundle/vim-airline/autoload/airline/extensions/wordcount.vim
87: ~/.vim/bundle/vim-airline/autoload/airline/extensions/tmuxline.vim
88: ~/.vim/bundle/vim-mundo/autoload/airline/extensions/mundo.vim
89: ~/.vim/bundle/vim-airline/autoload/airline/section.vim
90: ~/.vim/bundle/vim-airline/autoload/airline/highlighter.vim
91: ~/.vim/bundle/vim-airline/autoload/airline/themes/dark.vim
92: ~/.vim/bundle/vim-airline/autoload/airline/themes.vim
93: ~/.vim/bundle/vim-airline/autoload/airline/util.vim
99: ~/.vim/bundle/vim-airline/autoload/airline/builder.vim
100: ~/.vim/bundle/vim-airline/autoload/airline/extensions/default.vim
What I don't know (and what I think I need help with) is the location of the file :scriptnames references and how to remove duplicates.
Thanks for your thoughts.
Most Vim plugins consist of several script files. It is therefore normal to see multiple references in :scriptnames. In your output, the base Airline directory is ~/.vim/bundle/vim-airline; all of these base directories have a common substructure under them (usually autoload/... and plugin/...).
What the owner meant was to check for multiple base directories, e.g. both ~/.vim/bundle/vim-airline and ~/.vim/bundle/vim-another-airline. Based on your output, that doesn't seem to be the case. Also, the error is about the Mundo extension for Airline, not Airline itself. Shouldn't you then look for multiple installations of Mundo?!