fix: Improper appending of `Completion` script causes errors reading `.zshrc` file

[pattobrien]

Description

After the initial installation of cli_completion (used by my package sidecar_cli), on the next opening of a terminal window, I get the below failure message:

/Users/pattobrien/.zshrc:14: no matches found: [Completion]

This issue only occurs when the last line of my existing .zshrc file does not end in a return. If it ends in a return, the ## [Completion] line is put on the following line, and no error happens.

Steps To Reproduce

1. Have a pre-existing .zshrc file that does not end in a blank line/line return
2. Run a CLI command that uses cli_completion (e.g. sidecar init) - cli_completion is installed
3. Close the terminal window and open a new one. The above error will then be seen.

Expected Behavior

No error.

Additional Context

.zshrc file before using cli_completion (note: it does not end in a new line):

export PATH="/usr/local/opt/ruby/bin:$PATH"
export PATH="/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin"
export PATH="$PATH:${HOME}/fvm/default/bin"
# export PATH="$PATH:${HOME}/fvm/default/bin/dart"
# export PATH="$PATH:${HOME}/fvm/default/bin/cache/dart-sdk"
export PATH="$PATH:${HOME}/fvm/default/bin/cache/dart-sdk/bin"
export PATH="${HOME}/Library/Android/sdk/tools:${HOME}/Library/Android/sdk/platform-tools:${PATH}"
export PATH="/Library/Frameworks/Python.framework/Versions/3.9/bin:${PATH}"
eval $(/opt/homebrew/bin/brew shellenv)
export NVM_DIR="${HOME}/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"  # This loads nvm
export GEM_HOME="$HOME/.gem" 
export PATH="$PATH":"$HOME/.pub-cache/bin"
export PUB_CACHE="$HOME/.pub-cache"

.zshrc file AFTER using cli_completion:

export PATH="/usr/local/opt/ruby/bin:$PATH"
export PATH="/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin"
export PATH="$PATH:${HOME}/fvm/default/bin"
# export PATH="$PATH:${HOME}/fvm/default/bin/dart"
# export PATH="$PATH:${HOME}/fvm/default/bin/cache/dart-sdk"
export PATH="$PATH:${HOME}/fvm/default/bin/cache/dart-sdk/bin"
export PATH="${HOME}/Library/Android/sdk/tools:${HOME}/Library/Android/sdk/platform-tools:${PATH}"
export PATH="/Library/Frameworks/Python.framework/Versions/3.9/bin:${PATH}"
eval $(/opt/homebrew/bin/brew shellenv)
export NVM_DIR="${HOME}/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"  # This loads nvm
export GEM_HOME="$HOME/.gem" 
export PATH="$PATH":"$HOME/.pub-cache/bin"
export PUB_CACHE="$HOME/.pub-cache"## [Completion] 
## Completion scripts setup. Remove the following line to uninstall
[[ -f /Users/pattobrien/.dart-cli-completion/zsh-config.zsh ]] && . /Users/pattobrien/.dart-cli-completion/zsh-config.zsh || true
## [/Completion]

You can see that the ## [Completion] line is improperly appended to the previous line, rather than being given its own line.