Suppress errors on autocompletion for preload()
See https://github.com/godotengine/godot/issues/15766
Suppresses the errors that currently show up on each keypress in resource path completion, e.g.:
ERROR: _load: No loader found for resource: res://
At: core/io/resource_loader.cpp:190.
ERROR: _load: No loader found for resource: res://r
At: core/io/resource_loader.cpp:190.
ERROR: _load: No loader found for resource: res://re
At: core/io/resource_loader.cpp:190.
ERROR: _load: No loader found for resource: res://res
At: core/io/resource_loader.cpp:190.