error -> League\Flysystem\Filesystem::delete():

I have two almost the same controllers for update an item with uploading an image with filepond. The store function in both controllers.

One controller works and the other gives a error:

League\Flysystem\Filesystem::delete(): Argument #1 ($location) must be of type string, null given, called in /Users/antoine/Sites/TBV-TripleB/vendor/laravel/framework/src/Illuminate/Filesystem/FilesystemAdapter.php on line 504

Controller that works without errors

    public function edit(Sponsor $sponsor)
    {
        return view('admin.sponsors.edit', [
            'sponsor' => $sponsor,
        ]);
    }

public function update(Request $request, Sponsor $sponsor)
    {
        if (str()->afterLast($request->input('image'), '/') !== str()->afterLast($sponsor->image, '/')) {
            Storage::disk('public')->delete($sponsor->image);
            $newFilename = Str::after($request->input('image'), 'tmp/');
            Storage::disk('public')->move($request->input('image'), "sponsors/$newFilename");
        }

        $attributes = (array_merge($this->validateSponsor($sponsor), [
            'image' => isset($newFilename) ? "sponsors/$newFilename" : $sponsor->image
        ]));

        $sponsor->update($attributes);

        $request->session()->flash('success', 'Sponsor succesfully changed');

        return redirect()->route('admin.sponsors.index');
    }

protected function validateSponsor(?Sponsor $sponsor = null): array
    {
        $sponsor ??= new Sponsor();

        return request()->validate([
            'name' => [
                'required',
                'string',
                'max:255',
                Rule::unique('sponsors', 'name')->ignore($sponsor)
            ],
            'link' => [
                'required',
                'url',
                'max:255',
                Rule::unique('sponsors', 'link')->ignore($sponsor)
            ],
            'published' => [
                'nullable'
            ],
        ]);
    }

The controller that gives an error. The only difference is in the validation rules for password .

    public function edit(User $user)
    {
        return view('admin.members.edit', [
            'user' => $user,
        ]);
    }

public function update(Request $request, User $user)
    {
        if (str()->afterLast($request->input('image'), '/') !== str()->afterLast($user->profile_picture, '/')) {
            Storage::disk('public')->delete($user->profile_picture);
            $newFilename = Str::after($request->input('image'), 'tmp/');
            Storage::disk('public')->move($request->input('image'), "members/$newFilename");
        }

        $attributes = (array_merge($this->validateMember($user), [
            'profile_picture' => isset($newFilename) ? "members/$newFilename" : $user->profile_picture
        ]));

        $user->update($attributes);

        $request->session()->flash('success', 'Member succesfully changed');

        return redirect()->route('admin.members.index');
    }

protected function validateMember(?User $user = null): array
    {
        $user ??= new User();

        return request()->validate([
            'username' => [
                'required',
                'string',
                'alpha_dash',
                'max:255',
                Rule::unique('users', 'username')->ignore($user)
            ],
            'email' => [
                'required',
                'string',
                'email',
                'max:255',
                Rule::unique('users', 'email')->ignore($user)
            ],
            'password' => $this->passwordRules(),
        ]);
    }

The line that is highlighted is:

Storage::disk('public')->delete($user->profile_picture);

Please help, because I don't get it.