Change use of debug from as constructor to call directly

[ColaFanta]

The default export of debug package is now as a function instead of a class.
https://github.com/debug-js/debug/blob/6b2c5fbdb7d414483d9e306ef234acb4cd7ea67c/src/common.js#L7

Use debug as class works most of the time but may cause error under some strict environment. This PR fixes this by changing the use of debug from class to function.

[panva]

may cause error under some strict environment

Can you please be specific?

[ColaFanta]

I am using node-oidc-provider on Cloudflare Workers and have successfully adapted this library to the Workers WebAPI environment. However, I still encounter the following error, which this PR fixes:

TypeError: Debug is not a constructor  
(file:///.../lib/shared/error_handler.js:10:14)  

The reason behind this error may be due to using Debug as a constructor. In lib/shared/error_handler.js, the usage is as follows:

//...  
import Debug from 'debug'  
//...  
const debug = new Debug('oidc-provider:error')  

Meanwhile, in the source code of the debug npm package, the default export is defined like this:

function setup(env) {  
	createDebug.debug = createDebug;  
	createDebug.default = createDebug;  
	createDebug.coerce = coerce;  
	createDebug.disable = disable;  
	...  
	return createDebug;  
}  

module.exports = setup;  

I am currently applying this patch in my project and everything works fine, so I hope this change can be merged into the official repo.

[panva]

@ColaFanta I'm not opposed to adjusting the usage of debug but you need to first report this discrepency in https://github.com/cloudflare/workerd.

[panva]

And FWIW the only supported oidc-provider runtime is Node.js