Early return in render_textpic leaves registers unrestored
In the CssStyledContentController class there is the method render_textpic.
On the one hand it contains the feature "preRenderRegisters" in line 474 and line 1076, which makes use of LOAD_REGISTER.
On the other hand it contains two early returns in line 488 and 493.
So having an empty image list or a list of images with empty values will leave the loaded registers unrestored.
Solution: Always restore the registers before returning.
I didn't check, if this is already the same for earlier versions, but the reporter of #56536 mentioned at least TYPO3 6.1 to behave similarly.
Patch will follow immediately.