Variable shadows build in uniform: rainStrength

java.lang.Exception: Variable shadows build in uniform: rainStrength
    at net.coderbot.iris.uniforms.custom.CustomUniforms.addVariable(CustomUniforms.java:175) ~[iris-mc1.20-1.6.4.jar:?]
    at net.coderbot.iris.uniforms.custom.CustomUniforms.<init>(CustomUniforms.java:56) ~[iris-mc1.20-1.6.4.jar:?]
    at net.coderbot.iris.uniforms.custom.CustomUniforms$Builder.build(CustomUniforms.java:317) ~[iris-mc1.20-1.6.4.jar:?]
    at net.coderbot.iris.uniforms.custom.CustomUniforms$Builder.build(CustomUniforms.java:329) ~[iris-mc1.20-1.6.4.jar:?]
    at net.coderbot.iris.pipeline.newshader.NewWorldRenderingPipeline.<init>(NewWorldRenderingPipeline.java:254) ~[iris-mc1.20-1.6.4.jar:?]
    at net.coderbot.iris.Iris.createPipeline(Iris.java:676) ~[iris-mc1.20-1.6.4.jar:?]
    at net.coderbot.iris.pipeline.PipelineManager.preparePipeline(PipelineManager.java:34) ~[iris-mc1.20-1.6.4.jar:?]
    at net.minecraft.class_310.handler$cjh000$iris$resetPipeline(class_310.java:18043) ~[client-intermediary.jar:?]
    at net.minecraft.class_310.method_18097(class_310.java) ~[client-intermediary.jar:?]
    at net.minecraft.class_310.method_1481(class_310.java:2147) ~[client-intermediary.jar:?]
    at net.minecraft.class_634.method_11117(class_634.java:1114) ~[client-intermediary.jar:?]
    at net.minecraft.class_2724.method_11782(class_2724.java:78) ~[client-intermediary.jar:?]
    at net.minecraft.class_2724.method_11054(class_2724.java:16) ~[client-intermediary.jar:?]
    at net.minecraft.class_2600.method_11072(class_2600.java:22) ~[client-intermediary.jar:?]
    at net.minecraft.class_1255.method_18859(class_1255.java:156) ~[client-intermediary.jar:?]
    at net.minecraft.class_4093.method_18859(class_4093.java:23) ~[client-intermediary.jar:?]
    at net.minecraft.class_1255.method_16075(class_1255.java:130) ~[client-intermediary.jar:?]
    at net.minecraft.class_1255.method_5383(class_1255.java:115) ~[client-intermediary.jar:?]
    at net.minecraft.class_310.method_1523(class_310.java:1175) ~[client-intermediary.jar:?]
    at net.minecraft.class_310.method_1514(class_310.java:802) ~[client-intermediary.jar:?]
    at net.minecraft.client.main.Main.main(Main.java:250) ~[fabric-loader-0.14.21-1.20.1.jar:?]
    at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:468) ~[fabric-loader-0.14.21.jar:?]
    at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:74) ~[fabric-loader-0.14.21.jar:?]
    at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23) ~[fabric-loader-0.14.21.jar:?]