shell - Invalid string: control characters from U+0000 through U+001F must be escaped using Bash?

I have a function like:

getServers() {
    curl -s -X GET ...
}

The output is a complex JSON string. I can parse the JSON like this:

serverId=$(getServers | jq -r ".[] | select(whatever...)")
echo $serverId

But if I store the output of the function call in a variable, I get an error:

servers=$(getServers)
echo $servers | jq .
# jq can not process this
# parse error: Invalid string: control characters from U+0000 through             

echo "$servers" | jq .
# does not work either

U+001F must be escaped at line ...

Even though I $servers contain the same value as function call, jq fails to process it. What's happening here?

$ jq --version
jq-1.5

Possible Answer

Pipe the string into tr '\r\n' ' ':

servers=$(getServers)
echo $servers | tr '\r\n' ' ' | jq .