Silence source map warnings

When running `yarn start`, the console would complain:

WARNING in ./node_modules/react-diff-view/es/index.js
Module Warning (from ./node_modules/source-map-loader/dist/cjs.js):
Failed to parse source map from ‘~/react-native-upgrade-helper/node_modules/react-diff-view/src/utils/parse.ts' file: Error: ENOENT: no such file or directory, open ‘~/react-native-upgrade-helper/node_modules/react-diff-view/src/utils/parse.ts'

Author: markrickert

config-overrides.js

@@ -1,3 +1,13 @@
 const { override, addBabelPreset } = require('customize-cra')
 
-module.exports = override(addBabelPreset('@emotion/babel-preset-css-prop'))
+const ignoreWarnings = (value) => (config) => {
+  config.ignoreWarnings = value
+  return config
+}
+
+module.exports = override(
+  addBabelPreset('@emotion/babel-preset-css-prop'),
+
+  // Ignore warnings about the react-diff-view sourcemap files.
+  ignoreWarnings([/Failed to parse source map/])
+)