fix: throw an error if Vitest cannot access its internal state (#3250)

packages/vitest/src/integrations/vi.ts

@@ -168,6 +168,16 @@ function createVitest(): VitestUtils {
   let _config: null | ResolvedConfig = null
 
   const workerState = getWorkerState()
+
+  if (!workerState) {
+    const errorMsg = 'Vitest failed to access its internal state.'
+      + '\n\nOne of the following is possible:'
+      + '\n- "vitest" is imported directly without running "vitest" command'
+      + '\n- "vitest" is imported inside "globalSetup" (to fix this, use "setupFiles" instead, because "globalSetup" runs in a different context)'
+      + '\n- Otherwise, it might be a Vitest bug. Please report it to https://github.com/vitest-dev/vitest/issues\n'
+    throw new Error(errorMsg)
+  }
+
   const _timers = new FakeTimers({
     global: globalThis,
     config: workerState.config.fakeTimers,