Shader error when loading glb models

[Sceat]

This weird errors appears while loading the glb characters models

THREE.WebGLProgram: Shader Error 0 - VALIDATE_STATUS false

Material Name: 
Material Type: MeshDepthMaterial

Program Info Log: Vertex shader is not compiled.
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VERTEX

ERROR: 0:448: 'MORPHTARGETS_COUNT' : undeclared identifier
ERROR: 0:448: '' : array size must be a constant integer expression
ERROR: 0:450: 'MORPHTARGETS_COUNT' : undeclared identifier
ERROR: 0:450: '<' : wrong operand types - no operation '<' exists that takes a left-hand operand of type 'highp int' and a right operand of type 'const highp float' (or there is no acceptable conversion)
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  443: 	mat4 boneMatY = getBoneMatrix( skinIndex.y );
  444: 	mat4 boneMatZ = getBoneMatrix( skinIndex.z );
  445: 	mat4 boneMatW = getBoneMatrix( skinIndex.w );
  446: #endif
  447: #ifdef USE_INSTANCING_MORPH
> 448: 	float morphTargetInfluences[MORPHTARGETS_COUNT];
  449: 	float morphTargetBaseInfluence = texelFetch( morphTexture, ivec2( 0, gl_InstanceID ), 0 ).r;
  450: 	for ( int i = 0; i < MORPHTARGETS_COUNT; i ++ ) {
  451: 		morphTargetInfluences[i] =  texelFetch( morphTexture, ivec2( i + 1, gl_InstanceID ), 0 ).r;
  452: 	}
  453: #endif
  454: 	#ifdef USE_DISPLACEMENTMAP

It is often hidden (for ease of development) by using

renderer.debug.checkShaderErrors = false

[piellardj]

I believe this is a bug introduced in three.js v162 (see mrdoob/three.js#27669).
Here is a PR to add a workaround: #46