fix(eslint-plugin): [prefer-optional-chain] fixer produces wrong logic

packages/eslint-plugin/src/rules/prefer-optional-chain.ts

@@ -221,10 +221,19 @@ export default util.createRule({
 
         if (expressionCount > 1) {
           if (previous.right.type === AST_NODE_TYPES.BinaryExpression) {
+            let operator = previous.right.operator;
+            if (
+              previous.right.operator === '!==' &&
+              previous.right.right.type === AST_NODE_TYPES.Literal &&
+              previous.right.right.raw === 'null'
+            ) {
+              // case like foo !== null && foo.bar !== null
+              operator = '!=';
+            }
             // case like foo && foo.bar !== someValue
-            optionallyChainedCode += ` ${
-              previous.right.operator
-            } ${sourceCode.getText(previous.right.right)}`;
+            optionallyChainedCode += ` ${operator} ${sourceCode.getText(
+              previous.right.right,
+            )}`;
           }
 
           context.report({

packages/eslint-plugin/tests/rules/prefer-optional-chain.test.ts

@@ -123,6 +123,22 @@ const baseCases = [
     code: 'foo.bar && foo.bar?.() && foo.bar?.().baz',
     output: 'foo.bar?.()?.baz',
   },
+  {
+    code: 'foo !== null && foo.bar !== null',
+    output: 'foo?.bar != null',
+  },
+  {
+    code: 'foo != null && foo.bar != null',
+    output: 'foo?.bar != null',
+  },
+  {
+    code: 'foo != null && foo.bar !== null',
+    output: 'foo?.bar != null',
+  },
+  {
+    code: 'foo !== null && foo.bar != null',
+    output: 'foo?.bar != null',
+  },
 ].map(
   c =>
     ({