_this.logger.warning is not a function

I’m submitting a…

[ ] Regression (a behavior that used to work and stopped working in a new release)
[X] Bug report  
[ ] Performance issue
[ ] Feature request
[ ] Documentation issue or request
[ ] Other... Please describe:

Browser:

• Chrome version 74.0.3729.157
• Firefox version 66.0.5
• IE version XX
• Edge version XX
• Safari version XX

Library version

Library version: 1.0.1 (latest at this date of 24.5.19)



## Current behavior
I added logging as per https://docs.microsoft.com/en-us/azure/active-directory/develop/msal-logging to end up with:

                    ```
logger: {
    localCallback: loggerCallback,
    level: LogLevel.Verbose,
    piiLoggingEnabled: true,
    correlationId: '1234',
}
```

I saw this error in the browser console:

```
core.js:15724 ERROR Error: Uncaught (in promise): TypeError: _this.logger.warning is not a function
TypeError: _this.logger.warning is not a function
    at UserAgentApplication.js:471
    at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invoke (zone.js:391)
    at Object.onInvoke (core.js:17299)
```

I had to add ALL logger fields to remove this error and get the application working.

```
logger: {
                        localCallback: loggerCallback,
                        level: LogLevel.Verbose,
                        piiLoggingEnabled: true,
                        correlationId: '1234',
                        logMessage: loggerCallback,
                        executeCallback: loggerCallback,
                        errorPii: singleMessage,
                        error: singleMessage,
                        warning: singleMessage,
                        warningPii: singleMessage,
                        info: singleMessage,
                        infoPii: singleMessage,
                        verbose: singleMessage,
                        verbosePii: singleMessage
}
```

## Expected behavior
I would think that most of those fields are optional - they could default to an already given loggerCallback.  Or the doco could be updated to say they need to be populated also.

I also added a comment to that https://docs.microsoft.com/en-us/azure/active-directory/develop/msal-logging page to say it isn't showing all the fields of Logger (before I discovered the error).

## Minimal reproduction of the problem with instructions
Follow https://docs.microsoft.com/en-us/azure/active-directory/develop/msal-logging

[oehm-smith]

Specifically I now have:

        const loggerCallback = (logLevel, message, containsPii) => {
            console.log(`Auth: [${logLevel} ${message}`);
        };
        const logger = new Logger(
            loggerCallback,
            {correlationId: '1234', level: LogLevel.Info, piiLoggingEnabled: true});

        const data = await this.getIds();

        this.msal = new UserAgentApplication(
            {
                auth: {
                    clientId: data.clientId,
                    authority: 'https://login.microsoftonline.com/organizations',
                    redirectUri: Uri + '/login',
                },
                cache: {
                    cacheLocation: 'localStorage',
                    storeAuthStateInCookie: true
                },
                system: {
                    logger
                }
            }
        );

[gauravgoyal5]

Is this working?