Check return value of command in if bash statement

I have a simple script that tries to curl and URL and echo a string if it failed or succeeded. But I get the following warnings, depending on how I form this if statement.

Depending on the quotes I use in the statement below I get the following warnings:

: -ne: unary operator expected
: integer expression expected

With the alternative check (as comment), I get the following error

((: != 0 : syntax error: operand expected (error token is "!= 0 ")

The script:

c=`curl -s -m 10 https://example.com` || ce=$?

#if (( ${je} != 0 )); then 
if [ ${ce} -ne 0 ]; then 
        echo "Failed"
else
        echo "Succeeded"
fi

How do I correctly check the return value of the curl command in a bash if-statement?