Absolute webapp paths produce confusing error message

[mlenkeit]

When configuring custom webapp paths as described in the docs and using absolute paths, karma-ui5 produces a confusing error message.

Error message:

Could not find defined path to your "webapp" folder.

Please check if the configured path is correct:

module.exports = function(config) {
	config.set({

		ui5: {
			type: "application",
			paths: {
				webapp: "/xxx/openui5-sample-app/webapp" 	<-- Not found
			}
		}

	});
};

Sample config

const path = require("path");

module.exports = function(config) {
	"use strict";

	config.set({

		frameworks: ["ui5"],

		browsers: ["Chrome"],

		browserConsoleLogOptions: {
			level: "error"
		},

		ui5: {
			type: "application",
			paths: {
				// webapp: "webapp" // <-- works
				webapp: path.resolve(__dirname, "webapp") // <-- does not work
			}
		}

	});
};

Repo/branch to reproduce:

https://github.com/mlenkeit/openui5-sample-app/tree/absolute-path-bug

Expected behavior:
a) it just works (preferred), or
b) it returns an error that absolute paths are not allowed (not to difficult with path.isAbsolute), or at least
c) adjust the docs to state that it has to be a relative path