I've had issues with crashes in a custom modpack and after removing mods until the crashing stopped, then readded the ones until I crashed again, I have found that ElecCore was causing issues with other mods. https://gist.github.com/skellitor301/1e1efff8fd97f22211d371bb94c2d1a2
this was on the 1.14.4 version of Minecraft, all mods are confirmed up to date for version 1.14.4, that was a potential issue brought up with IronChests showing 1.14.3 but that's not the case.

It is possible that this is ElecCore, though this log doesn't confirm anything.

Next time this comes up, please post the entire log, as this might hav happened because of a crash that happened earlier

(I cannot reproduce this unfortunately)

I have a similar problem. Here's my latest.log file for ya, apparently there's an incompatibility issue or something...
latest.log

Mods: Aquaculture, Create, ElecCore, JEI, MixinBootstrap, More Player Models, Optifine (via OptiForge), Simple Farming, and Water Strainer

EDIT: Not the same issue but extremely similar in nature
EDIT2: I've recently discovered that none of the mods listed require ElecCore as a dependent, making this error all the more confusing. Considering moving this comment to a new thread. Please note I am using the 1.14.4 version.

Mines crashing too on both of the 1.14 versions of elec core and the launcher isn't even getting far enough along that the crash generates a proper crash log.

I've had issues with crashes in a custom modpack and after removing mods until the crashing stopped, then readded the ones until I crashed again, I have found that ElecCore was causing issues with other mods. https://gist.github.com/skellitor301/1e1efff8fd97f22211d371bb94c2d1a2
this was on the 1.14.4 version of Minecraft, all mods are confirmed up to date for version 1.14.4, that was a potential issue brought up with IronChests showing 1.14.3 but that's not the case.

For your crash it looks like it is related with doggy talent mod... If you read the top few lines of the crash report, it says when doggy talent mod is registering block colors it crashed...

I've had issues with crashes in a custom modpack and after removing mods until the crashing stopped, then readded the ones until I crashed again, I have found that ElecCore was causing issues with other mods. https://gist.github.com/skellitor301/1e1efff8fd97f22211d371bb94c2d1a2
this was on the 1.14.4 version of Minecraft, all mods are confirmed up to date for version 1.14.4, that was a potential issue brought up with IronChests showing 1.14.3 but that's not the case.

For your crash it looks like it is related with doggy talent mod... If you read the top few lines of the crash report, it says when doggy talent mod is registering block colors it crashed...

It's actually not, I've had this issue before with other mods, even if I remove doggy talents other mods start having issues. Only after removing ElecCore and keeping the other mods it keeps having issues with does it work. All I can say is for some reason ElecCore creates issues regarding registerBlockColours and other mods, as that's the only common thing I find between each crash.