Console Spam: ########## GL ERROR ########## ; @ Post render ; 1286: Invalid framebuffer operation

Summary: Pausing Minecraft and Minimizing the window will cause the console to constantly write the following:

[Client thread/ERROR]: ########## GL ERROR ##########
[Client thread/ERROR]: @ Post render
[Client thread/ERROR]: 1286: Invalid framebuffer operation

I've been experiencing this since 15w51b, if Minecraft is lagging too, this will come up:

[Client thread/ERROR]: ########## GL ERROR ##########
[Client thread/ERROR]: @ Post render
[Client thread/ERROR]: 1286: Invalid framebuffer operation
[Client thread/WARN]: Something's taking too long! 'root.gameRenderer.level.terrain.render_Solid' took aprox 449.770913 ms
[Client thread/WARN]: Something's taking too long! 'root.gameRenderer.level.terrain' took aprox 461.483944 ms
[Client thread/WARN]: Something's taking too long! 'root.gameRenderer.level' took aprox 474.739275 ms
[Client thread/WARN]: Something's taking too long! 'root.gameRenderer' took aprox 506.825792 ms
[Client thread/WARN]: Something's taking too long! 'root' took aprox 508.339349 ms

The type of lag doesn't necessarily have to be a level.terrain, but you get the general idea.

To Reproduce:
1. Open a Minecraft World.
2. Pause Minecraft.
3. Minimize the window.

Notes:
1. Based on testing & reproducing this issue, this may not happen on some machines, OS's or Java versions.
2. Game outputs are attached files, these are two instances of it happening.