fix(server): switch to sync write
fix(server): switch to sync write

The async write operation has no callback and errors are not
detected that way. Switch to the sync version to circumvent that
problem.
karma-runner/karma,maksimr/karma,david-garcia-nete/karma,johnjbarton/karma,johnjbarton/karma,karma-runner/karma,david-garcia-nete/karma,david-garcia-nete/karma,johnjbarton/karma,maksimr/karma,johnjbarton/karma,maksimr/karma,karma-runner/karma,karma-runner/karma