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/@jest/core/tsconfig.json

@@ -0,0 +1,27 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "build"
+  },
+  "references": [
+    {"path": "../jest-changed-files"},
+    {"path": "../jest-config"},
+    {"path": "../jest-console"},
+    {"path": "../jest-haste-map"},
+    {"path": "../jest-message-util"},
+    {"path": "../jest-regex-util"},
+    {"path": "../jest-reporters"},
+    {"path": "../jest-resolve-dependencies"},
+    {"path": "../jest-runner"},
+    {"path": "../jest-runtime"},
+    {"path": "../jest-snapshot"},
+    {"path": "../jest-test-result"},
+    {"path": "../jest-test-sequencer"},
+    {"path": "../jest-types"},
+    {"path": "../jest-transform"},
+    {"path": "../jest-util"},
+    {"path": "../jest-validate"},
+    {"path": "../jest-watcher"}
+  ]
+}