Mods may be incompatible with each other or arranged incorrectly (in the launcher you have a "mods" tab and some mods require them to be, for example, the latest one)
Also try installing mods via Nexus mods because apparently there are fewer crash problems.

Yup, it's tough getting modules to work mate. For me it's also crashing, the launcher warns me beforehand that it needs specific versions of some modules like Harmony v2.2.2.0 which I have, but unfortunately Steam apparently doesn't detect them.