If you find that BBEdit is unable to locate commands that you are able to use in Terminal; or if you find that these commands are available but behave unexpectedly, it's likely that your shell environment needs to be adjusted so that your customizations are visible to BBEdit. (This applies to language servers as well as commands such as
svn that BBEdit uses to support built-in features.)
zsh, a common mistake is to configure
$PATH and other environment variables in
zsh only loads
~/.zshrc when running an interactive shell. Because BBEdit runs
zsh as a non-interactive shell,
zsh does not load
~/.zshrc, and BBEdit never gets your desired environment.
However, if you move
$PATH (and other environment settings) into
zsh will load this (in BBEdit as well as in Terminal).
Note that you can also use
~/.zshenv, since BBEdit runs
zsh as a login shell to determine the appropriate environment.
A detailed description of the configuration files that
zsh uses can be found in sections 5.1 and 5.2 of the zsh documentation.