zmathfunc: min, max, sum throw error if result equals 0

["Nikolaus Thiel" <klt@fsfe.org>]

There seems to be a bug in zmathfunc:

When the result of min, max or sum equals 0, the functions throw an error. If
they are used within a script with the option "set -e" then the script aborts,
cf. test script below.

I have confirmed this behaviour on two systems:


(1) Apple MacBook Air, Ubuntu 20.04.2 LTS

Linux Luftbuch 5.4.0-66-generic #74-Ubuntu SMP Wed Jan 27 22:54:38 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
zsh 5.8 (x86_64-ubuntu-linux-gnu)


(2) Apple iMac, macOS 11.2.2

Darwin Kernel Version 20.3.0: Thu Jan 21 00:07:06 PST 2021; root:xnu-7195.81.3~1/RELEASE_X86_64
zsh 5.8 (x86_64-apple-darwin20.0)



-------- Test Script --------

#!/usr/bin/env zsh
set -e
OS=$(uname)
if [[ ${OS} == "Darwin" ]]; then
    ### Mac OS X
    source /usr/share/zsh/5.8/functions/zmathfunc
else
    ### Ubuntu 20.04
    source /usr/share/zsh/functions/Math/zmathfunc
fi

echo "OS = ${OS}"
zsh --version

echo "works fine"

x=$(( min(2,-1,3) ))
echo "min(2,1,3)  = $((x))"
x=$(( max(2,-1,3) ))
echo "max(2,-1,3) = $((x))"
x=$(( sum(2,-1,3) ))
echo "sum(2,-1,3) = $((x))"


echo "min, max, sum throw an error if result=0"
echo " => set -e causes script to abort"

x=$(( sum(-2,2) ))
echo "sum(-2,2)  = $((x))"

x=$(( min(2,0,3) ))
echo "min(2,0,3)  = $((x))"

x=$(( max(-2,0,-3) ))
echo "max(-2,0,-3)  = $((x))"



-------- Output on Mac OS X --------
OS = Darwin
zsh 5.8 (x86_64-apple-darwin20.0)
works fine
min(2,1,3)  = -1
max(2,-1,3) = 3
sum(2,-1,3) = 4
min, max, sum throw an error if result=0
 => set -e causes script to abort


-------- Output on Ubuntu --------
OS = Linux
zsh 5.8 (x86_64-ubuntu-linux-gnu)
works fine
min(2,1,3)  = -1
max(2,-1,3) = 3
sum(2,-1,3) = 4
min, max, sum throw an error if result=0
 => set -e causes script to abort