ESLint: enable recommended rules (graphql#1515)

Based on this list: https://github.com/eslint/eslint/blob/caeb223c4f7b0b6fe35e5348ae0df4c6446b5bed/conf/eslint-recommended.js

Author: IvanGoncharov

.eslintrc.yml

@@ -74,11 +74,11 @@ rules:
  # Possible Errors
  # https://eslint.org/docs/rules/#possible-errors
 
- #for-direction: undecided
- #getter-return: undecided
+ for-direction: error
+ getter-return: error
  #no-async-promise-executor: undecided
  no-await-in-loop: error
- #no-compare-neg-zero: undecided
+ no-compare-neg-zero: error
  no-cond-assign: error
  no-console: warn
  no-constant-condition: error
@@ -105,7 +105,7 @@ rules:
  #no-template-curly-in-string: undecided
  no-unexpected-multiline: off
  no-unreachable: error
- #no-unsafe-finally: undecided
+ no-unsafe-finally: error
  no-unsafe-negation: error
  #require-atomic-updates: undecided
  use-isnan: error
@@ -130,19 +130,20 @@ rules:
  #max-classes-per-file: undecided
  no-alert: error
  no-caller: error
- #no-case-declarations: undecided
+ # TODO: recommended rule but disable due to errors in existing code
+ # no-case-declarations: error
  no-div-regex: error
  no-else-return: error
  #no-empty-function: undecided
- #no-empty-pattern: undecided
+ no-empty-pattern: error
  no-eq-null: off
  no-eval: error
  no-extend-native: error
  no-extra-bind: error
  #no-extra-label: undecided
  no-fallthrough: error
  no-floating-decimal: off
- #no-global-assign: undecided
+ no-global-assign: error
  no-implicit-coercion: error
  #no-implicit-globals: undecided
  no-implied-eval: error
@@ -166,13 +167,13 @@ rules:
  no-return-assign: error
  #no-return-await: undecided
  no-script-url: error
- #no-self-assign: undecided
+ no-self-assign: error
  no-self-compare: off
  no-sequences: off
  no-throw-literal: error
  #no-unmodified-loop-condition: undecided
  no-unused-expressions: error
- #no-unused-labels: undecided
+ no-unused-labels: error
  no-useless-call: error
  #no-useless-concat: undecided
  no-useless-escape: error
@@ -326,14 +327,14 @@ rules:
  #arrow-body-style: undecided
  arrow-parens: off
  arrow-spacing: off
- #constructor-super: undecided
+ constructor-super: error
  generator-star-spacing: off
  no-class-assign: error
  #no-confusing-arrow: undecided
  no-const-assign: error
- #no-dupe-class-members: undecided
+ no-dupe-class-members: error
  #no-duplicate-imports: undecided
- #no-new-symbol: undecided
+ no-new-symbol: error
  #no-restricted-imports: undecided
  no-this-before-super: error
  #no-useless-computed-key: undecided