Stops calling existsSync on object configs (jestjs#7607)

Author: arcanis

CHANGELOG.md

@@ -52,6 +52,7 @@
 
 ### Fixes
 
+- `[jest-config]` Ensure `existsSync` is only called with a string parameter ([#7607](https://github.com/facebook/jest/pull/7607))
 - `[expect]` `toStrictEqual` considers sparseness of arrays. ([#7591](https://github.com/facebook/jest/pull/7591))
 - `[jest-cli]` Fix empty coverage data for untested files ([#7388](https://github.com/facebook/jest/pull/7388))
 - `[jest-cli]` [**BREAKING**] Do not use `text-summary` coverage reporter by default if other reporters are configured ([#7058](https://github.com/facebook/jest/pull/7058))

packages/jest-config/src/index.js

@@ -286,6 +286,7 @@ export function readConfigs(
       .filter(root => {
         // Ignore globbed files that cannot be `require`d.
         if (
+          typeof root === 'string' &&
           fs.existsSync(root) &&
           !fs.lstatSync(root).isDirectory() &&
           !root.endsWith('.js') &&