Check if EditorConfig file exist for Ktlint in KotlinGradleExtension

Follow up 959fd85.

Author: Goooler

plugin-gradle/CHANGES.md

@@ -5,6 +5,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ## [Unreleased]
 ### Fixed
 * Fix Eclipse JDT on some settings files. ([#1864](https://github.com/diffplug/spotless/pull/1864) fixes [#1638](https://github.com/diffplug/spotless/issues/1638))
+* Check if EditorConfig file exist for Ktlint in KotlinGradleExtension. ([#1889](https://github.com/diffplug/spotless/pull/1889)
 ### Changes
 * Bump default `ktlint` version to latest `1.0.0` -> `1.0.1`. ([#1855](https://github.com/diffplug/spotless/pull/1855))
 ### Fixed

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/KotlinGradleExtension.java

@@ -74,11 +74,14 @@ public class KotlinFormatExtension {
 		}
 
 		public KotlinFormatExtension setEditorConfigPath(Object editorConfigPath) throws IOException {
-
 			if (editorConfigPath == null) {
 				this.editorConfigPath = null;
 			} else {
-				this.editorConfigPath = FileSignature.signAsList(getProject().file(editorConfigPath));
+				File editorConfigFile = getProject().file(editorConfigPath);
+				if (!editorConfigFile.exists()) {
+					throw new IllegalArgumentException("EditorConfig file does not exist: " + editorConfigFile);
+				}
+				this.editorConfigPath = FileSignature.signAsList(editorConfigFile);
 			}
 			replaceStep(createStep());
 			return this;