Improve exception message

detekt-core/src/main/kotlin/io/gitlab/arturbosch/detekt/core/Analyzer.kt

@@ -155,6 +155,7 @@ private fun MutableMap<String, List<Finding>>.mergeSmells(other: Map<String, Lis
 private fun throwIllegalStateException(file: KtFile, error: Throwable): Nothing {
     val message = """
     Analyzing ${file.absolutePath()} led to an exception. 
+    Location: ${error.stackTrace.firstOrNull()?.toString()}
     The original exception message was: ${error.localizedMessage}
     Running detekt '${whichDetekt() ?: "unknown"}' on Java '${whichJava()}' on OS '${whichOS()}'
     If the exception message does not help, please feel free to create an issue on our GitHub page.

detekt-core/src/test/kotlin/io/gitlab/arturbosch/detekt/core/AnalyzerSpec.kt

@@ -86,6 +86,34 @@ class AnalyzerSpec {
 
             assertThat(settings.use { analyzer.run(listOf(compileForTest(testFile))) }).isEmpty()
         }
+
+        @Test
+        fun `with faulty rule`() {
+            val testFile = path.resolve("Test.kt")
+            val settings = createProcessingSettings(
+                testFile,
+                yamlConfig("configs/config-value-type-correct.yml")
+            )
+            val analyzer = Analyzer(settings, listOf(FaultyRuleSetProvider()), emptyList())
+
+            assertThatThrownBy { settings.use { analyzer.run(listOf(compileForTest(testFile))) } }
+                .hasCauseInstanceOf(IllegalStateException::class.java)
+                .hasMessageContaining("Location: ${FaultyRule::class.java.name}")
+        }
+
+        @Test
+        fun `with faulty rule without stack trace`() {
+            val testFile = path.resolve("Test.kt")
+            val settings = createProcessingSettings(
+                testFile,
+                yamlConfig("configs/config-value-type-correct.yml")
+            )
+            val analyzer = Analyzer(settings, listOf(FaultyRuleNoStackTraceSetProvider()), emptyList())
+
+            assertThatThrownBy { settings.use { analyzer.run(listOf(compileForTest(testFile))) } }
+                .hasCauseInstanceOf(IllegalStateException::class.java)
+                .hasMessageContaining("Location: ${null}")
+        }
     }
 }
 
@@ -106,3 +134,29 @@ private class MaxLineLength(config: Config, threshold: Int?) : Rule(config) {
         }
     }
 }
+
+private class FaultyRuleSetProvider : RuleSetProvider {
+    override val ruleSetId: String = "style"
+    override fun instance(config: Config) = RuleSet(ruleSetId, listOf(FaultyRule(config)))
+}
+
+private class FaultyRule(config: Config) : Rule(config) {
+    override val issue = Issue(this::class.java.simpleName, Severity.Style, "", Debt.FIVE_MINS)
+    override fun visitKtFile(file: KtFile) {
+        throw object : IllegalStateException("Deliberately triggered error.") {}
+    }
+}
+
+private class FaultyRuleNoStackTraceSetProvider : RuleSetProvider {
+    override val ruleSetId: String = "style"
+    override fun instance(config: Config) = RuleSet(ruleSetId, listOf(FaultyRuleNoStackTrace(config)))
+}
+
+private class FaultyRuleNoStackTrace(config: Config) : Rule(config) {
+    override val issue = Issue(this::class.java.simpleName, Severity.Style, "", Debt.FIVE_MINS)
+    override fun visitKtFile(file: KtFile) {
+        throw object : IllegalStateException("Deliberately triggered error without stack trace.") {
+            init { stackTrace = emptyArray() }
+        }
+    }
+}

detekt-core/src/test/resources/configs/config-value-type-correct.yml

@@ -2,3 +2,7 @@ style:
   MaxLineLength:
     active: true
     maxLineLength: 120
+  FaultyRule:
+    active: true
+  FaultyRuleNoStackTrace:
+    active: true