Proposed API and build improvements #45

Thanks for publishing this library, have been using it a quite heavily over the last few months to record frontend errors in the same place as we track backend problems. Out of this, I'd like to submit some improvements, some of which may require some discussion and decisions, so this is a meta issue for tracking the proposed changes.

Library API

Currently StackdriverErrorReporter exposes a callback parameter in a few places, mostly to enable the testing. This allows some errors to be seen by callers, but does not expose the extracted stacktrace message and is somewhat awkward to use. As stacktrace-js already uses promises, I suggest the interface here should too. The promise api is widely available and there's a polyfill bundled in the build already (though this may want some tweaking, see below).

• Return a Promise from report() and sendErrorPayload() Return a Promise from report method #50
• Propagate payload (or just payload.message) when promise is fulfilled Give clear results when report promise completes #59
• Add config option to output message to console.log Unhandled exception should still be printed to the Console #6
• Handle non-200 HTTP responses report() should allow handling of non-200 Stackdriver responses #32

When calling report() directly from a logging framework, stacktraces for strings currently start inside the logger rather than at the caller.

• Expose firstFrameIndex as an argument to report() Add option to skip more frames using report #58

Build and packaging

This is a simple library and doesn't need a complicated build, but there are a few niggles currently when embedding in a modern webapp, and the single file bundle could also been improved. Not sure how far to go on this front, but there are some simple improvements to make at least.

• Update devDependencies to latest versions Update devDependencies to latest versions #49
• Remove 'dist' folder from version control Unversion dist folder and generate in prepare #48
• Make npm start launch the demo in a browser window Show demo in browser on npm start #52
• Enable ES6 import without hack Provide JS module #2