Added checks to make sure the specified track exists

Added precondition checks to validate input files and paths to return more informative error messages as per #2

node_modules/prompts/dist/util/figures.js

@@ -0,0 +1,32 @@
+'use strict';
+
+const main = {
+  arrowUp: '↑',
+  arrowDown: '↓',
+  arrowLeft: '←',
+  arrowRight: '→',
+  radioOn: '◉',
+  radioOff: '◯',
+  tick: '✔',
+  cross: '✖',
+  ellipsis: '…',
+  pointerSmall: '›',
+  line: '─',
+  pointer: '❯'
+};
+const win = {
+  arrowUp: main.arrowUp,
+  arrowDown: main.arrowDown,
+  arrowLeft: main.arrowLeft,
+  arrowRight: main.arrowRight,
+  radioOn: '(*)',
+  radioOff: '( )',
+  tick: '√',
+  cross: '×',
+  ellipsis: '...',
+  pointerSmall: '»',
+  line: '─',
+  pointer: '>'
+};
+const figures = process.platform === 'win32' ? win : main;
+module.exports = figures;