When providing a non existent file to a Shader component it attempts to compile it with the error: 

Failed to read shader code from :/qt/qml/debug_qml/nosuchfile.frag
QSpirvCompiler: Failed to parse shader
Failed to compile fragment shader: ERROR: :193: 'qt_customMain' : no matching overloaded function found 
ERROR: :193: '' : compilation terminated 
ERROR: 2 compilation errors.  No code generated.

"effect pipeline-->DEFAULT>:9aed8cb44c112cc5a5cc98b4840ddf50f28eac47:1:1:0" 

It took me about one hour to realize this mistake, because I had assumed that I was missing qt modules, or had a broken installation. The engine should realize that the provided file does not exist, not even attempt to compile the shader and print a proper warning/error to the user.

Sample code:

import QtQuick
import QtQuick3D

Window 
{
    visible: true

    Shader
    {
        id: shd
        stage: Shader.Fragment
        shader: "nosuchfile.frag"
    }

    View3D
    {
        anchors.fill: parent

        OrthographicCamera {}

        environment: SceneEnvironment
        {
            effects: Effect { passes: Pass { shaders: shd } }
        }
    }
}