[FIX] Print error cause stack trace

The CLI now also prints the stack trace of the error cause of
unexpected errors or when verbose logging is enabled.

This improves error analysis in case an error is caught and re-thrown
as "cause" of a new error, e.g. during minification.

lib/cli/base.js

@@ -108,6 +108,11 @@ export default function(cli) {
 						process.stderr.write("\n");
 						process.stderr.write(err.stack);
 						process.stderr.write("\n");
+						if (err.cause instanceof Error && err.cause.stack) {
+							process.stderr.write(chalk.underline("Error Cause Stack Trace:\n"));
+							process.stderr.write(err.cause.stack + "\n");
+							process.stderr.write("\n");
+						}
 						process.stderr.write(
 							chalk.dim(
 								`If you think this is an issue of the UI5 Tooling, you might report it using the ` +