Opening project/material using visual shader instance uniforms results in many errors failure to compile shaders

[lostminds]

Godot version

v4.2.beta1.official [b137180]

System information

Godot v4.2.beta1 - macOS 13.6.0 - Vulkan (Mobile) - integrated Apple M2 Pro - Apple M2 Pro (10 Threads)

Issue description

It appears something has broken in compiling shaders (maybe visual shaders) using instance shader uniforms in the Mobile renderer. Opening a scene where one is used gives me the following errors:

servers/rendering/renderer_rd/forward_mobile/scene_shader_forward_mobile.cpp:183 - Condition "!shader_singleton->shader.version_is_valid(version)" is true.
  servers/rendering/renderer_rd/forward_mobile/scene_shader_forward_mobile.cpp:183 - Condition "!shader_singleton->shader.version_is_valid(version)" is true.
  servers/rendering/renderer_rd/shader_rd.cpp:293 - Error compiling Fragment shader, variant #2 (
  #define MODE_RENDER_DEPTH
  ).
  servers/rendering/renderer_rd/shader_rd.cpp:294 - Failed parse:
 WARNING: 0:73: '' : all default precisions are highp; use precision statements to quiet warning, e.g.:
           "precision mediump int; precision highp float;" 
  ERROR: 0:1763: 'instance_index' : undeclared identifier 
  ERROR: 0:1763: '[]' : scalar integer expression required 
  ERROR: 0:1763: '' : compilation terminated 
  ERROR: 3 compilation errors.  No code generated.

Followed by 27000+ error lines of what looks like complete printouts of some very long godot internal shaders like servers/rendering/renderer_rd/shader_rd.cpp

Considering the number of shader compilation errors lines, perhaps it would be a good idea to limit the output of full shader code? As this probably does not contribute to making the issue easier to find and also slows down the interface a little in cases like this.

Steps to reproduce

Open the attached empty project with just a material referencing a visual shader.
If it's not selected already, select the material in the FileSystem browser to get the errors.

Minimal reproduction project

InstanceShaderTest.zip

[clayjohn]

Duplicate of #83391

Fixed by #83400