diff --git a/packages/eslint-plugin/tests/rules/prefer-optional-chain/prefer-optional-chain.test.ts b/packages/eslint-plugin/tests/rules/prefer-optional-chain/prefer-optional-chain.test.ts
index 91e908015fbb..eddfd57bb994 100644
--- a/packages/eslint-plugin/tests/rules/prefer-optional-chain/prefer-optional-chain.test.ts
+++ b/packages/eslint-plugin/tests/rules/prefer-optional-chain/prefer-optional-chain.test.ts
@@ -1946,24 +1946,66 @@ describe('hand-crafted cases', () => {
           declare const thing1: string | null;
           thing1 && thing1.toString();
         `,
+        output: null,
         options: [{ requireNullish: true }],
-        errors: [{ messageId: 'preferOptionalChain' }],
+        errors: [
+          {
+            messageId: 'preferOptionalChain',
+            suggestions: [
+              {
+                messageId: 'optionalChainSuggest',
+                output: `
+          declare const thing1: string | null;
+          thing1?.toString();
+        `,
+              },
+            ],
+          },
+        ],
       },
       {
         code: `
           declare const thing1: string | null;
           thing1 && thing1.toString() && true;
         `,
+        output: null,
         options: [{ requireNullish: true }],
-        errors: [{ messageId: 'preferOptionalChain' }],
+        errors: [
+          {
+            messageId: 'preferOptionalChain',
+            suggestions: [
+              {
+                messageId: 'optionalChainSuggest',
+                output: `
+          declare const thing1: string | null;
+          thing1?.toString() && true;
+        `,
+              },
+            ],
+          },
+        ],
       },
       {
         code: `
           declare const foo: string | null;
           foo && foo.toString() && foo.toString();
         `,
+        output: null,
         options: [{ requireNullish: true }],
-        errors: [{ messageId: 'preferOptionalChain' }],
+        errors: [
+          {
+            messageId: 'preferOptionalChain',
+            suggestions: [
+              {
+                messageId: 'optionalChainSuggest',
+                output: `
+          declare const foo: string | null;
+          foo?.toString() && foo.toString();
+        `,
+              },
+            ],
+          },
+        ],
       },
       {
         code: `
@@ -1994,24 +2036,66 @@ describe('hand-crafted cases', () => {
           declare const foo: string | null;
           (foo || {}).toString();
         `,
+        output: null,
         options: [{ requireNullish: true }],
-        errors: [{ messageId: 'preferOptionalChain' }],
+        errors: [
+          {
+            messageId: 'preferOptionalChain',
+            suggestions: [
+              {
+                messageId: 'optionalChainSuggest',
+                output: `
+          declare const foo: string | null;
+          foo?.toString();
+        `,
+              },
+            ],
+          },
+        ],
       },
       {
         code: `
           declare const foo: string;
           (foo || undefined || {}).toString();
         `,
+        output: null,
         options: [{ requireNullish: true }],
-        errors: [{ messageId: 'preferOptionalChain' }],
+        errors: [
+          {
+            messageId: 'preferOptionalChain',
+            suggestions: [
+              {
+                messageId: 'optionalChainSuggest',
+                output: `
+          declare const foo: string;
+          (foo || undefined)?.toString();
+        `,
+              },
+            ],
+          },
+        ],
       },
       {
         code: `
           declare const foo: string | null;
           (foo || undefined || {}).toString();
         `,
+        output: null,
         options: [{ requireNullish: true }],
-        errors: [{ messageId: 'preferOptionalChain' }],
+        errors: [
+          {
+            messageId: 'preferOptionalChain',
+            suggestions: [
+              {
+                messageId: 'optionalChainSuggest',
+                output: `
+          declare const foo: string | null;
+          (foo || undefined)?.toString();
+        `,
+              },
+            ],
+          },
+        ],
       },
 
       // allowPotentiallyUnsafeFixesThatModifyTheReturnTypeIKnowWhatImDoing
diff --git a/packages/typescript-estree/src/create-program/createProjectService.ts b/packages/typescript-estree/src/create-program/createProjectService.ts
index c355033191c4..b63273ad1265 100644
--- a/packages/typescript-estree/src/create-program/createProjectService.ts
+++ b/packages/typescript-estree/src/create-program/createProjectService.ts
@@ -48,10 +48,10 @@ export function createProjectService(
     logger: {
       close: doNothing,
       endGroup: doNothing,
-      getLogFileName: () => undefined,
-      hasLevel: () => false,
+      getLogFileName: (): undefined => undefined,
+      hasLevel: (): boolean => false,
       info: doNothing,
-      loggingEnabled: () => false,
+      loggingEnabled: (): boolean => false,
       msg: doNothing,
       perftrc: doNothing,
       startGroup: doNothing,