org.gradle.api.GradleScriptException: A problem occurred evaluating root project 'waco'.
Caused by: net.minecraftforge.gradle.util.GradleConfigurationException: There are no mappings for MC 1.12.2
forge version - 1.12.2-14.23.5.2855
mappings - 'stable_39'
org.gradle.api.GradleScriptException: A problem occurred evaluating root project 'waco'. Caused by: net.minecraftforge.gradle.util.GradleConfigurationException: There are no mappings for MC 1.12.2
forge version - 1.12.2-14.23.5.2855 mappings - 'stable_39'
how do I fix this