When I try to build/run my mod, it spits out an error and doesn't work

Console Error -

Executing gradle command: setupDecompWorkspace --refresh-dependencies
Build info: MCreator 1.9.1, 64-bit, 8114 MB, Windows 10 - cmd, JVM 1.8.0_222, JAVA_HOME: C:\Program Files\Pylo\MCreator\jdk
C:\Users\user\MCreatorWorkspaces\coiled>gradlew -Dorg.gradle.java.home="C:/Program Files/Pylo/MCreator/jdk" -Dorg.gradle.parallel=false -Dorg.gradle.jvmargs="-Xms625m -Xmx2048m" setupDecompWorkspace --refresh-dependencies 
Starting a Gradle Daemon, 3 busy and 1 incompatible and 1 stopped Daemons could not be reused, use --status for details
This mapping 'snapshot_20171003' was designed for MC 1.12! Use at your own peril.
FAILURE: Build failed with an exception.
* What went wrong:
A problem occurred configuring root project 'coiled'. < My Mod
> java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
BUILD FAILED in 49s
C:\Users\jayco\MCreatorWorkspaces\coiled>
Task completed with return code 0 in 50492 milliseconds

I've tried deleting certain elements, uninstalling and re-installing MCreator and making a new workspace. so far nothing's worked, and I was wondering if anyone else had this problem