don't warn on undefined

Author: FSVetaz

demo/test/snapshots/lint-output.js.md

@@ -1911,7 +1911,7 @@ Generated by [AVA](https://ava.li).
           "error"␊
         ],␊
         "no-undefined": [␊
-          "warn"␊
+          "off"␊
         ],␊
         "no-underscore-dangle": [␊
           "error",␊
@@ -3644,8 +3644,6 @@ Generated by [AVA](https://ava.li).
        39:18  error    Unnecessary use of boolean literals in conditional expression                                                                  no-unneeded-ternary␊
        39:18  warning  Unexpected constant condition                                                                                                  no-constant-condition␊
        42:7   warning  Correct one of the identical sub-expressions on both sides of operator "&&"                                                    sonarjs/no-identical-expressions␊
-       42:18  warning  Unexpected use of undefined                                                                                                    no-undefined␊
-       42:42  warning  Unexpected use of undefined                                                                                                    no-undefined␊
        42:55  error    'params' is not defined                                                                                                        no-undef␊
        43:5   warning  This function expects 1 argument, but 2 were provided                                                                          sonarjs/no-extra-arguments␊
        44:30  error    Module path/to/legacyModule is deprecated. Use module x instead                                                                deprecate/import␊
@@ -3701,6 +3699,6 @@ Generated by [AVA](https://ava.li).
       18:96  warning  Delete `;`                                                                                    prettier/prettier␊
       20:2   warning  Delete `;`                                                                                    prettier/prettier␊
     ␊
-    ✖ 79 problems (35 errors, 44 warnings)␊
+    ✖ 77 problems (35 errors, 42 warnings)␊
       4 errors and 6 warnings potentially fixable with the `--fix` option.␊
     `

demo/test/snapshots/lint-output.js.snap

@@ -20,7 +20,6 @@ module.exports = {
     'no-case-declarations': 'off', // frontier has this as error
     'no-else-return': 'off', // frontier has this as error
     'no-prototype-builtins': 'warn', // frontier has this as error
-    'no-undefined': 'warn', // frontier has this as error
     'prefer-const': 'warn', // frontier has this as error
 
     'no-warning-comments': [
@@ -32,6 +31,7 @@ module.exports = {
     'no-shadow': 'warn', // frontier has this as error, tw-blue has this as off
 
     'valid-jsdoc': ['warn'], // frontier has this as off
+    'no-undefined': 'off', // frontier has this as off, we had this as warn. I think it really should be off which means removing this line.
 
     'jsdoc/check-access': 'off',
     'jsdoc/check-alignment': 'warn',