[fish] exit as well when called from non-interactive shell

Just like with the other shells, exit fish to, if called from a non-interactive
shell.

We use an `if`-block and don’t just return immediately for now, as older
versions of fish (namely < 3.4.0) did not support to use `return` in `.`-scripts
(this was only added with fish commit 3359e5d2e9bcbf19d1652636c8e448a6889302ae).

Just using `exit` instead of a `return` wouldn’t be a proper solution either, as
it would exit the whole shell, when `shell/key-bindings.fish` was executed or
sourced from a non-interactive shell.
While this should of course never happen, the idea of the whole check is to
handle the situation gracefully, which `exit` can thus not do.

Signed-off-by: Christoph Anton Mitterer <[email protected]>

shell/key-bindings.fish

@@ -11,6 +11,9 @@
 # - $FZF_ALT_C_COMMAND
 # - $FZF_ALT_C_OPTS
 
+if status is-interactive
+
+
 # Key bindings
 # ------------
 function fzf_key_bindings
@@ -170,3 +173,6 @@ function fzf_key_bindings
   end
 
 end
+
+
+end