fix: show fallback message for typescript jest preset if ts-jest is not installed (#6418)

Co-authored-by: Haoqun Jiang <haoqunjiang@gmail.com>

closes #6383

Author: m0ksem

packages/@vue/cli-plugin-unit-jest/presets/typescript/jest-preset.js

@@ -1,12 +1,19 @@
 const deepmerge = require('deepmerge')
 const defaultPreset = require('../default/jest-preset')
 
+let tsJest = null
+try {
+  tsJest = require.resolve('ts-jest')
+} catch (e) {
+  throw new Error('Cannot resolve "ts-jest" module. Typescript preset requires "ts-jest" to be installed.')
+}
+
 module.exports = deepmerge(
   defaultPreset,
   {
     moduleFileExtensions: ['ts', 'tsx'],
     transform: {
-      '^.+\\.tsx?$': require.resolve('ts-jest')
+      '^.+\\.tsx?$': tsJest
     }
   }
 )