Doctrine Dbal Table not altered

Although i have added doctrine/dbal in composer.json and updated composer but even then facing an error

Integrity Constraint Violation: 1062 Duplicate entry '' for key ' users_oauthprovider_id_unique

  Schema::table('users', function (Blueprint $table) {
            $table->string('password')->nullable()->change();
            $table->string('oauthprovider');
            $table->string('oauthprovider_id')->unique();
        });

via Asif Nawaz