I nearly lost my mind over the PPSSPP crashin issue yesterday. But now I finally got it working.
Maybe my problem is different from what others here experience, but as I said, an older version of the core from a month ago still worked for me. So what I did was loading my PSP games with the old core file, setting up the game config for each game I have and saving it.
Today I downloaded the newest nightly and it works. To make sure that the missing config files were definitely the issue I deleted one of the game config files again and yep, the game crashes on boot.
I can finally play GTA LCS again, it runs quite well on Switch with max overclock and looks better than it did on PSP. Set "Auto Frameskip" to "ON", leave the other frameskip settings at "0", set the resolution to "960x544", and set "Disable slower effects (Speedhack) to "ON".
The current PPSSPP core is 244a601, downloaded today.
Can you save and load save states?