Error: "This rule requires the strictNullChecks compiler option to be turned on to function correctly @typescript-eslint/strict-boolean-expressions"

[el-leonya]

Package version: 19.0.1
OS: Kubuntu 20:10; Node.js: 14.10.0; npm: 6.14.8

What happened?
I'm not sure if it's a bug, or if I might misunderstand something. This is minimal project to reproduce the problem.

git clone https://github.com/ljonya/ts-app.git
cd ts-app
npm i
npx eslint ./test.ts 

Prints out an error:

/home/leonid/ts-app/test.ts
  0:1  error  This rule requires the `strictNullChecks` compiler option to be turned on to function correctly  @typescript-eslint/strict-boolean-expressions

✖ 1 problem (1 error, 0 warnings)

Although in tsconfig.json the property strictNullChecks is true.

[jtalcantara]

Same here, :(

Node: v14.15.0; npm: 6.14.8

[theoludwig]

Same problem while working for https://github.com/standard/vscode-standardjs/.
Maybe related to this PR : typescript-eslint/typescript-eslint#2345

EDIT: I fixed it by explicitly setting strict: true, in the tsconfig.json of the root of the subfolders of typescript projects.
Example for the vscode extension there are 2 subfolders : client and server and at the root there is a tsconfig.json with strict: true, but it wasn't enough, I also needed to set it in the tsconfig.json of the client and the server folders. Hopefully I'm clear and it's helping to find out how to solve the issue.

[chantzlarge]

Found that defining the project explicity using:

ts-standard -p ./tsconfig.json

In my Angular project resolved this error for me.

[juliancioc]

try to close and open the vscode :)

[LucasMallmann]

try to close and open the vscode :)

Always works :) (worked after setting the strictNullChecks in the tsconfig.json file).

[ghost]

Add "strictNullChecks": true to the "compilerOptions" object in tsconfig.json did the trick

[HenriqueOmena]

don't forget to reload your VsCode when u change 'strictNullChecks' to true to not receive this error message anymore

[theoludwig]

As others said, please enable strictNullChecks in tsconfig.json.
Will close the issue for now, but please reopen if you have any doubt or others issues. 😄

[VictorMeneghini]

try to close and open the vscode :)

Best solution... Always works hahaha

[geraldoam]

try to close and open the vscode :)

Thanks!

[JoanWilson]

try to close and open the vscode :)

Thank you!! Best Solution

[lenodeoliveira]

@LucasMallmann
Best solution!

[Vanilagy]

You don't need to reload/restart VS Code. Simply restarting the TS language server will suffice.
CTRL/CMD + SHIFT + P -> Typescript: Restart TS server

[JayDouglass]

Same problem while working for https://github.com/standard/vscode-standardjs/. Maybe related to this PR : typescript-eslint/typescript-eslint#2345

EDIT: I fixed it by explicitly setting strict: true, in the tsconfig.json of the root of the subfolders of typescript projects. Example for the vscode extension there are 2 subfolders : client and server and at the root there is a tsconfig.json with strict: true, but it wasn't enough, I also needed to set it in the tsconfig.json of the client and the server folders. Hopefully I'm clear and it's helping to find out how to solve the issue.

I had a similar problem in a new Vite/React/TS project. I had to set strict: true in tsconfig.node.json.