Please help with WebGL errors

Hi, i successfully made simple code that creates sprite and adds it to root stage. But i keep getting errors in console:

Quote

Error: WebGL: Exceeded 16 live WebGL contexts for this principal, losing the least recently used one.
Error: WebGL: texImage2D: Conversion requires pixel reformatting.
Error: WebGL: drawElements: This operation requires zeroing texture data. This is slow.

What do they mean, and how to fix them ?