src/vs/base/common/uri.ts/_validateUri
function _validateUri(ret: URI, _strict?: boolean): void {

	// scheme, must be set
	if (!ret.scheme && _strict) {
		throw new Error(`[UriError]: Scheme is missing: {scheme: "", authority: "${ret.authority}", path: "${ret.path}", query: "${ret.query}", fragment: "${ret.fragment}"}`);
	}

	// scheme, https://tools.ietf.org/html/rfc3986#section-3.1
	// ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
	if (ret.scheme && !_schemePattern.test(ret.scheme)) {
		throw new Error('[UriError]: Scheme contains illegal characters.');
	}

	// path, http://tools.ietf.org/html/rfc3986#section-3.3
	// If a URI contains an authority component, then the path component
	// must either be empty or begin with a slash ("/") character.  If a URI
	// does not contain an authority component, then the path cannot begin
	// with two slash characters ("//").
	if (ret.path) {
		if (ret.authority) {
			if (!_singleSlashStart.test(ret.path)) {
				throw new Error('[UriError]: If a URI contains an authority component, then the path component must either be empty or begin with a slash ("/") character');
			}
		} else {
			if (_doubleSlashStart.test(ret.path)) {
				throw new Error('[UriError]: If a URI does not contain an authority component, then the path cannot begin with two slash characters ("//")');
			}
		}
	}
}