Send Logger.Level.ERROR logs to STDERR

src/Logger.ts

@@ -6,13 +6,21 @@ class Logger {
     }
 
     /**
-     * Print object without any log level
+     * Print object without any log level to STDOUT
      * @param obj Object to print
      */
-    private send(...obj: any[]): void {
+    private stdout(...obj: any[]): void {
         console.log(...obj);
     }
 
+    /**
+     * Print object without any log level to STDERR
+     * @param obj Object to print
+     */
+    private stderr(...obj: any[]): void {
+        console.error(...obj);
+    }
+
     /**
      * Format string with log level and prefix
      * @param level Log level
@@ -29,7 +37,7 @@ class Logger {
      * @param [obj] Objects to print
      */
     public log(level: Logger.Level, message: string, ...obj: any[]): void {
-        this.send(this.format(level, message), ...obj);
+        this[level === Logger.Level.ERROR ? "stderr" : "stdout"](this.format(level, message), ...obj);
     }
 
     /**