refactor: make command argument checking into guard claus.

mc

@@ -99,8 +99,12 @@ function main() {
     if [[ ! $(which curl) ]]; then echo "curl is required"; exit 1; fi
     if [[ ! $(which jq) ]]; then echo "jq is required"; exit 1; fi
     
-    for command in "${!commands[@]}"; do
-        if [[ "$1" == "${command}" ]]; then
+    # Check if key does NOT exists in command array
+    if [[ ! -v commands[$1] ]]; then
+        printf "${0}: invalid option -- $1\n"
+        usage
+        exit 1
+    fi
 
     local endpoint method body
     read -r endpoint method body <<<"${commands[$1]}"
@@ -124,12 +128,6 @@ function main() {
     esac
  
     exit 0
-        fi
-    done
-    
-    printf "${0}: invalid option -- $1\n"
-    usage
-    exit 1
 }