QOpenGLShader::compile(Fragment): ERROR: 0:8: '' : No precision specified for (float) 

*** Problematic Fragment shader source code ***
#ifndef GL_FRAGMENT_PRECISION_HIGH
#define highp mediump
#endif
varying highp vec2 sampleCoord;                            
uniform lowp sampler2D texture;                            
uniform lowp float color; // just the alpha, really...     
void main() {                                              
    vec4 glyph = texture2D(texture, sampleCoord);          
    gl_FragColor = vec4(glyph.rgb * color, glyph.a);       
} 
***
Renderer failed shader compilation: 
"" 
The program has unexpectedly finished.