plugins break when re-sourcing .zshrc after login

[rebelot]

Description

Hi all, I am quite new to ZSH. I have latest releases of antigen, zsh and oh-my-zsh. everything is working quite well, but I have encountered a minor annoying bug:

whenever I modify my .zshrc and I run source ~/.zshrc some of my plugins/themes break, namely git-prompt RPS1 and antigen autocompletion itself (i.e. typing antigen <tab> doesn't show autocomps, but many other autocompletions still work). also, when I was experimenting with themes, I remember I had to quit and reopen my shell after switching a few themes for things to come back to normal (sourcing wouldn't work)

moreover I find the "plugin already installed" warning annoying so I aliased alias initsh="source ~/.zshrc > /dev/null"

I am not sure if this is an Antigen issue, but you may know what is happening!

relevant extract of .zshrc:

source $ZSH/oh-my-zsh.sh

# init Antigen
source "$HOME/.antigen/antigen.zsh"

# Load the oh-my-zsh's library.
antigen use oh-my-zsh

# plugins
antigen bundle common-aliases
antigen bundle osx
antigen bundle catimg
antigen bundle colored-man-pages   
antigen bundle $ZSH/custom/plugins/git-prompt
antigen bundle srijanshetty/zsh-pandoc-completion
antigen bundle zsh-users/zsh-syntax-highlighting
antigen bundle zsh-users/zsh-completions

# end of Antigen configuration
antigen apply

btw, my customization of the plugin only consists in changing the symbols.