add comments and find a way to make it clearer that the types are correct.

Author: toger5

src/logger.ts

@@ -128,18 +128,25 @@ interface PrefixedLogger extends loglevel.Logger, LoggerWithLogMethod {
  *
  * @param prefix Prefix to add to each logged line. If undefined, no prefix will be added.
  */
-function getPrefixedLogger(prefix?: string): LoggerWithLogMethod {
+function getPrefixedLogger(prefix?: string): PrefixedLogger {
     const loggerName = DEFAULT_NAMESPACE + (prefix === undefined ? "" : `-${prefix}`);
     const prefixLogger = loglevel.getLogger(loggerName) as PrefixedLogger;
-
+    // This is a save cast since export const logger is constructed with getPrefixedLogger
+    // It is downcastet to `Logger` to minimize the public/exported api.
     if (prefixLogger.getChild === undefined) {
         // This is a new loglevel Logger which has not been turned into a PrefixedLogger yet.
         prefixLogger.prefix = prefix;
         prefixLogger.getChild = (childPrefix): Logger => {
-            const childLogger = getPrefixedLogger((prefix ?? "") + childPrefix) as unknown as loglevel.Logger;
-            childLogger.methodFactory = (logger as unknown as loglevel.Logger).methodFactory;
-            childLogger.setLevel(childLogger.getLevel());
-            return childLogger as unknown as Logger;
+            const rootLogger = logger as PrefixedLogger;
+            // create the new child logger
+            const childLogger = getPrefixedLogger((prefix ?? "") + childPrefix);
+            // assign the same methodFactory as the root logger.
+            // this is useful if we add extensions to the root logger that modify
+            // its methodFactory. (an example extension is: storing each log to a rageshake db)
+            childLogger.methodFactory = rootLogger.methodFactory;
+            // rebuild the child logger with the new methodFactory.
+            childLogger.rebuild();
+            return childLogger as Logger;
         };
         prefixLogger.setLevel(loglevel.levels.DEBUG, false);
     }
@@ -151,7 +158,7 @@ function getPrefixedLogger(prefix?: string): LoggerWithLogMethod {
  * Drop-in replacement for `console` using {@link https://www.npmjs.com/package/loglevel|loglevel}.
  * Can be tailored down to specific use cases if needed.
  */
-export const logger = getPrefixedLogger();
+export const logger = getPrefixedLogger() as LoggerWithLogMethod;
 
 /**
  * A "span" for grouping related log lines together.