Renaming a sketch that contains a .h and .cpp file leads to a crash and loosing the sketch.

[LagdasP]

Describe the bug
Renaming an .ino sketch with 3 tabs (the sketch and a .cpp/.h) resulted in the whole project disappearing after showing a dialogue about too many handles (it appeared briefly, didn't have the chance to read it). Instead, a new library was created in the libraries directory, that the header file had only a few first lines and the .cpp was completely empty.

To Reproduce
Steps to reproduce the behavior:

1. Create a sketch with a .cpp and .h tabs
2. Add some code to the .cpp .h tabs
3. Rename the sketch using the menu (top right) inside the IDE.

Expected behavior
To rename the selected tab.

Screenshots
Not applicable.

Desktop (please complete the following information):

• OS: OSX
• Version: 10.14.6

Additional context
Add any other context about the problem here.

[KurtE]

I reproduced this today using daily build 0708.

I had the IDE up and running. I did a File->New to create a new sketch.
In this case I tried saving the sketch to folder in my case: (Sketch Folder)/Teensy Tests/TestFlexFS

I added two new table: SimpleFlashFS.h and SimpleFlashFS.cpp to the sketch.

I then decided the sketch should be named Test_SimpleFlashFS so I went up to rename it.
The IDE brought up Save like dialog, so I typed in new name.
The Dialog exited, and then the Arduino window sort of blanked white, then sort of setup like a new empty sketch and
the Arduino IDE busy type indicator... I left it for several minutes and then killed the window.

I noted that the new sketch name did not exist, but did find the original sketch name in my sketch folder, which was empty.
I also found some stuff up in my temp directory, still with first name.

Have not checked the contents of the files to see what actually was there. In this case not a big deal as it is just an experiment