fixes the e.replace is not a function error happening on production in Firefox during createInstance

in js, any object can be thrown. that is why the `catch` block `error` variable has type `unknown` in typescript. in optimizely, there are a few catch blocks where the error variable is directly logged as message. in the logger, the type of the public named logging functions is `string | Error` which is not correct since it could actually be any type. if it is an object that is not an instance of type Error, this will cause a throw in `internalLog -> format -> sprintf` because sprintf is calling `.replace` on the message, which throws with `e.replace is not a function`. we have seen this exact error a lot in production. so logging causes a throw which causes createInstance to fail, causing further issues.

this PR fixes the issue by converting non-string and non-Error log messages to string first.

fixes #719

Author: fabb

packages/logging/src/logger.ts

@@ -264,15 +264,25 @@ class OptimizelyLogger implements LoggerFacade {
     }
   }
 
-  private namedLog(level: LogLevel, message: string | Error, splat: any[]): void {
+  private namedLog(level: LogLevel, message: unknown, splat: any[]): void {
     let error: Error | undefined
 
     if (message instanceof Error) {
       error = message
-      message = error.message
       this.internalLog(level, {
         error,
-        message,
+        message: error.message,
+        splat,
+      })
+      return
+    }
+
+    // sometimes values other than Error are thrown and logged with the optimizely logger,
+    // we need to catch this case here to avoid a follow-up issue when calling format/sprintf with something else than a string for the message
+    if (typeof message !== 'string') {
+      this.internalLog(level, {
+        error,
+        message: `${message}`,
         splat,
       })
       return