script file not found when using source - bash

Question

I have a bash script in a file named reach.sh.
This file is given exe rights using chmod 755 /Users/vb/Documents/util/bash/reach.sh.
I then created an alias using alias reach='/Users/vb/Documents/util/bash/reach.sh'
So far this works great.
It happens that I need to run this script in my current process, so theoretically I would need to add . or source before my script path.
So I now have alias reach='source /Users/vb/Documents/util/bash/reach.sh'
At this point when I run my alias reach, the script is failing.
Error /Users/vb/Documents/util/bash/reach.sh:7: = not found
Line 7 if [ "$1" == "cr" ] || [ "$1" == "c" ]; then
Full script
#!/bin/bash
# env
REACH_ROOT="/Users/vb/Documents/bitbucket/fork/self"
# process
if [ "$1" == "cr" ] || [ "$1" == "c" ]; then
echo -e "Redirection to subfolder"
cd ${REACH_ROOT}/src/cr
pwd
else
echo -e "Redirection to root folder"
cd ${REACH_ROOT}
pwd
fi
Any idea what I could be missing ?

Answer 1

I'm running my script in zsh which is not a bash shell, so when I force it to run in my current process it runs in a zsh shell and does not recognize bash commands anymore.

Answer 2

In your question, you say "It happens that I need to run this script in my current process", so I'm wondering why you are using source at all. Just run the script. Observe:
bash-script.sh
#!/bin/bash
if [ "$1" == "aaa" ]; then
echo "AAA"
fi
zsh-script.sh
#!/bin/zsh
echo "try a ..."
./bash-script.sh a
echo "try aaa ..."
./bash-script.sh aaa
echo "try b ..."
./bash-script.sh b
output from ./zsh-script.sh
try a ...
try aaa ...
AAA
try b ...
If, in zsh-script.sh, I put source in front of each ./bash-script.sh, I do get the behavior you described in your question.
But, if you just need to "run this script in my current process", well, then ... just run it.
source tries to read a file as lines to be interpreted by the current shell, which is zsh as you have said. But simply running it, causes the first line (the #!/bin/bash "shebang" line) to start a new shell that interprets the lines itself. That will totally resolve the use of bash syntax from within a zsh context.