Add friendly check for jq

Author: rsp2k

build-latest.sh

@@ -3,6 +3,15 @@
 
 echo "▶️ $0 $*"
 
+###
+# Check for the jq library needed for parsing JSON
+###
+if [ ! command -v jq &> /dev/null ]
+then
+    echo "⚠️ PRERELEASE must be either unset, 'true' or 'false', but was '${PRERELEASE}'!"
+    exit 1
+fi
+
 ###
 # Checking for the presence of GITHUB_OAUTH_CLIENT_ID
 # and GITHUB_OAUTH_CLIENT_SECRET